Amittai
Well, they are within the bounds of roleplay. To take on a roleplaying character is to take on the persona of another person of your own making. I can see how annoying looking at a vampire weregoose knight wizard can be, and the fact that the demon/half-demon characters are also far too prevalent, but it is perfectly within their bounds to play the part and at least pretend to believe they are what they roleplay as.
I usually find that in Roleplays, the same people who makes these kind of characters are the same ones who like to "God-Mod". Ie:
"Xdressvampitee rushes towards Normalcharacter, slicing his head from his body and laughing as it plops on the ground."
Only typically with much worse grammatical structure.