I'm against being against things.
The reason is simple: it's less effort to be against something; which makes it easier, but ultimately counter-productive.
What does this mean? Take relationships, for example. Suppose a woman states that she does not want to date a man who is abusive, which is a perfectly logical thing to want in a relationship. The problem, though, is that by making this her only criteria, she is opening herself up to a whole host of other types of bad relationships. She may indeed find a man who is not abusive, but he may be lazy, unattractive, rude, unhealthy, skips leg day, doesn't clean his room, has bad breath, etc. etc.
If you define your goals in terms of a negative, then you are basically dragging the bar down to a base level. If you are against something, then literally anything else will meet your defined requirements. And if anything else--even something only slightly better than your hard limit--can meet your standards, then that's probably what you will get.
I think we've seen this play out to some degree in politics. For years, negative campaigning has been the norm, and politicians (and their publicists) are usually pretty skilled in crafting some emotion-inducing attack ads on their opponents. That all seemed to come to a head this past presidential election with the choice between Hillary Clinton and Donald Trump, both of whom were heavily disliked by the general public, and had the lowest pre-election approval ratings in election history (since 1956, when the polls started). A good many people voted for Trump simply because he wasn't Hillary, and a good many people voted for Hillary simply because she wasn't Trump.
The reason the quality of politicians will inevitably decline with the increase in attack ads is basically a prisoner's dilemma game theory scenario. In a perfect world, two competing politicians would try to win the support of the public by being as good as they can be. But that's hard, and would basically be the unstable "mutual cooperation" case of the prisoner's dilemma. It's the best thing for everyone involved, but also the easiest to cheat. If one politician digs up some dirt on the other, then he/she knows that they don't have to be a model citizen anymore, they just have to be not as bad as their opponent. Politicians are thus incentivized to keep digging for dirt on their opponents, rather than trying to be good candidates themselves. The more dirt they have, the more leeway they have to be less than perfect on their own front, and the ultimate result is two shrewd psychopaths duking it out for a large amount of control over the public.
If the results are so undesirable, then why do negative attack ads continue to be the norm? Why are people so motivated to think negatively rather than positively?
Your Mind Is Wired To Make You Miserable
Psychology can explain it to some degree. Basically, our brains are wired to notice negative things more than positive ones. Have you ever gotten a bunch of compliments for something that you did, but one person said something that was maybe more of a criticism? I'll bet you remembered the criticism a lot more than you remembered the compliments.
The reason we do this is basically survival. The optimistic dreamers that were roaming through the forest and noticing things like nice pretty flowers and the sounds of sweet birds chirping probably didn't notice the wolf in the shadows that proceeded to eat them. They didn't survive long enough to reproduce, so their genes didn't get transmitted. The people who did survive were the ones that were constantly paranoid, and could notice the slightest bit of danger in an otherwise happy and peaceful scene.
Play To Win
In sports, a team or player can either "play to win" or "play not to lose". While the binary nature of sports results makes these two terms indistinguishable in theory, they are used to represent differences in strategy. A team that plays to win will usually stick to a game plan and take risks accordingly, whereas a team that plays "not to lose" will usually play more passively and try very hard not to give the other team easy points. Usually the latter strategy is adopted if a team has a big lead in a game, and can be effective, although it usually allows the opponent to work their way back in (as the Falcons so brilliantly displayed in the Super Bowl last year...which I'm totally over, by the way).
This is the thing I like (and sometimes hate) about tennis: it's a game in which you have to win. There's no time limit, and every point is equal. You can't just develop a lead and take your foot off the gas, you have to keep trying to play the same game that got you the lead in the first place. Like baseball and other such sports, there is no such thing as a "safe" lead in tennis (although usually being up a double-break in a set will suffice), but technically speaking, any deficit in tennis can be overcome.
If you play golf, you'll often come across shots in which there are hazards guarding the hole (lakes, sand traps, woods, etc.). The first thing people think is "oh no, don't hit it there!", and then they do one of two things: either they hit it exactly where they don't want to, or they overcompensate so much that they hit a shot so wayward it ends up in a parking lot across the street. You instead have to focus on hitting the shot exactly where you want to, and filter out all the obstacles (easier said than done).
If You Focus On The Positives, The Negatives Won't Be An Issue
Life should be approached in the same way as golf. If you only define yourself by the things you are against, then you won't do too much better than that (or do equally bad in the opposite direction). Be for something. Instead of being "anti-gun", talk instead about how generally safe your neighborhood is. Instead of being "anti-abortion", be truly "pro-life", i.e. talk about how awesome your kids are instead of complaining about them all the time.
Trying a new diet? Don't think about it in terms of foods you can't eat, think about it in terms of foods you can. If all you think about are foods you are missing out on, then you'll just be more tempted to eat them. If you go through the diet guidelines and say "oh, I can eat beef on this diet? Sweet, I love beef!" then it gives a positive direction for your mind to follow.
It works in relationships too: don't just seek someone who "isn't crazy" or "isn't ugly", have some standards for yourself. Now, when you set high standards, it's going to be hard to find someone who meets them exactly, and that's okay, because someone who doesn't quite live up to high standards is probably going to be better than someone who barely meets low standards. Just be sure you don't get so obsessed trying to find someone who meets your exact specifications that you end things with people you could be perfectly happy with.
The key in all this is that there is something positive to focus your efforts. It's okay to call out things that are bad in the world, it's okay to call out things that you wish were different, but have something to put in their place. There may be things you don't like about your house, but if you tear it down before you have a new house built, then you're just left with nothing.
Don't just burn things to the ground thinking it will solve your problems. It may feel good at first, but after the cathartic effect wears off you will be left emptier than before.
Focus your efforts on something productive, seek out something to build rather than something to destroy.
And if you don't like what a politician is generally about, then don't vote for them.