Again, not everyone may know this but one, usually slightly insulting term for an place of game play, especially for online usage is "Sandbox". As in "Let me play in your sandbox."
This usually only becomes an issue, and primarily an insult, in larger communities, especially ones which have had time to form a closed group of role players who may (or may not) have formed into an impenetrable unit who, although they may allow new characters to sign up, will then shut them out entirely to continue playing with their regular set. This may result in new 'groups' developing among the newer players, (these are often, but not always, more flexible than "The Regulars"), but it also tends to cause a high turnover rate of new players getting fed up with being ignored and leaving... assuming they could get in to the theoretically 'open for apps' system.
If you can legitimately say that you can't name a single older player who has actively interacted with people who aren't "One of the COOL/Special players", chances are you've got a sandbox group.
It's one thing if you've simply decided you REALLY don't like Joe-Shmoes new character, but then you should really stop and consider how Joe got into the rp in the first place. Does he have a ton of problems with his aplication? Were they not caught?
Is the application actually kind of ok and you just feel that interacting with Joe wouldn't be 'as awesome' as playing with The Regulars?
If the answer is the last one, stop and ask yourself: HOW DO YOU KNOW?
Even if you've rped with a totally different character of Joe's, you don't ALWAYS know you won't find a hidden gem. Granted there are some people who are just outright horrible roleplayers, for whatever reason happens to make them horrible roleplayers, but speaking from experience, and seeing dozens of people all over the place going "Wow... character A stunk horribly but their character B is freaking AWESOME."... I think I'm making a fairly legitimate point.
Also: If someone goes through the trouble of revising their profile multiple times in an clear effort to try and make their application fit the standards, and they do not have a background of problems that have caused them to be legitimately kicked from a setting, it's generally polite to give them a hand with trying to work out the application problems.
Seriously: Don't leave people hanging, either tell them to get out of your sandbox because it's YOUR sandbox, or show them what they're doing wrong. Not everyone will take your face off for it.