I am beyond picky when it comes to joining an rp. I look at it as if I was hiring someone. 

The interest check is the resume, if it isn't organized and well thought out I go right passed it to the next. 

Then there are the "references" and "background" checks; I check the Gm's posting history to see what other rps they have run and how they ran them, if I don't know the Gm I'll ask people that their thoughts are about the person. 

Now that isn't to say I won't give a new Gm a chance but I like to not only know the type of rp I am getting into but who I will be rping with.