The name of the RP is, of course, the first catch. If the name sets off warning bells in the reptilian part of my brain then I stay the fuck away from it. If it seems to mesh with my interests or tickles my curiosity then I check it out. Often, as long as the title doesn't sicken me, I tend to give things a look just for fun. No-brainer so far. For the record, I prefer a micro-summery of the game in the title but this is more of a nit-pick.
If the introduction post is, for whatever reason, difficult to read then I move on. There are some rare exceptions to this
@pugbutter. For the most part, my eyes are more important to me than your concept.
If a game requires the beautification of one's post, then you can fuck right off. As a personal rule of thumb, if it took longer to make the post template than it did to write the post itself, then the template is too fucking complicated. I don't even want "pretty" posts in my own games. Also, if you have a character sheet section and still require a picture for every post, then you can fuck right off.
If a game's character sheet is too complicated and arbitrary, then you can fuck right off. If it visibly took more effort to create the character sheet than it did to create the plot for your game, then your priorities are fucked.
I give zero fucks about "face claims". The game should not be about how people look. If a picture is more important to you than the player then your priorities are fucked.
Of course, the content of the game needs to mesh with what I want to play. That should go without saying but it is technically something that could turn me off toward a game. I'm trying to stay away from defining the content I prefer since it doesn't seem relevant.
Something that can make me lose interest at any point in the process are the other people who seem interested in the story. I do my damnedest to not give GMs the wrong impression toward my intentions. If I decide the people are not tolerable then I will gently let the GM know that it is time for me to depart.
If the GM doesn't live up to something they advertised then I might depart. This, sadly, has happened more than a few times.
I might take my leave if I feel like my personality will clash too much with other players. If I'm going to become the thorn in their side then I find it easier to just go somewhere else rather than risk ruining the fun for everybody else.
As far as I can tell, the majority of people who respond to an interest check will never make a second comment once the game goes live. I can accept that. I don't like it. Oh well.
This is less of a thing that scares me off and more of a gripe. I dislike when a potential GM finds a decent group and then just fades away. Depressing stuff, that.