I'm competing in a lot of the contests at Guru Shots lately, and competition can bring out some of your uglier emotions. I pretty much have to cast votes on other people's photos, every couple of hours, every day, to keep my pictures getting in front of other voters. A contest site like this can expose you to some wonderful new concepts if you let it. You just have to avoid focusing on the things that make you crazy.
The danger of these sites is that it's a competition, so you experience a lot of frustration, and frankly a lot of envy. You know your photo is good, so why can't other people see it? You'll find yourself thinking unhelpful thoughts along the lines of, "My pic is way better than that picture, right?" When you're casting votes with a bunch of negative emotions floating around in your head, things you see can really start to annoy you. You get annoyed by people posting off topic photos, or photos that aren't composed as well as your own "masterpiece" was. You forget that some of your own posts were just as bad as (if not worse than) what you're looking at. You forget that you stretched the definition of one of your own photos to questionably fit a contest theme too.
The photographers on Guru Shots who specialize in nudes can be particularly annoying. The nude is so often an exploitive medium that it's easy to forget that nudes can be tasteful and fit into a lot of themes. Looking at them, though, your own mindset matters a lot. It can feel like people are just trying to get votes with a pair of pretty eyes and a nice figure. They can make you feel bad for the model, if the picture is bad, and they can make you feel a little insulted. I tend to be harsher on nudes than on other types of photos because I don't like feeling manipulated. (I'm not even going to get into the porn trolls that inevitably pop up.)
Probably the worst effect is that frustration is cumulative. So somebody posts a bad nude and you get a little annoyed. Then the next photo you see has leading lines that don't lead to any visible subject in a competition named "Leading Lines". You're suddenly more annoyed with the second photo than you would have been before the bad nude. In today's online world, it can be tempting to go vent about this stuff on social media, but you really shouldn't. it's best to examine what you're feeling first. You'll find that, often, your indignation is mostly composed of frustration, and maybe even full on envy.
I guess the point of all of this is that contests can be wonderful sites to participate in, but you need to keep a firm grip on your frustration. Don't let it control you. Let your frustration power your desire to learn from the photos that consistently out score your own. Focus on what you can control, and let the votes fall where they fall. Go study more about Photoshop or Light Room. See different ways to accomplish your goal. Plan a shot more thoroughly than you otherwise would have. These solutions work better than venting your frustration. Take all that energy and put it to a better use. This is how you make your negative emotions pay off.