A big problem with Casual is that because it gets by far the most traffic, you get the widest range of player skills, and truth be told, many people are basically Free-level writers who are either trying to "move up" to Casual or don't want the stigma attached to it/ find parts of Free disagreeable, like speed posting, lack of organization, etc. Likewise, there's a lot of people in Casual who should be trying Advanced out but either feel it's an elitist snob haven or intimidating. These are the kinds of mindsets we should be trying to dispel and lead by example.
Anyways, I bring that up because you may be running into people who still are getting into roleplaying or are finally trying a game that has standards and don't really have experience in making a character, so they stick with what they know or like. Another potential issue I see far too often is people who approach RPing like a video game with classes, equipment values, and archtypes they need to fill plus a mindset of "I have to win".
Whatever the person or their reasons, the best way to approach it is to critique their sheet and point out what you find questionable without being rude or confrontational. Don't be afraid to demand effort from applicants, because if you force them to meet your expectations while showing you know what you're doing, you'll be left with generally solid players with diverse and interesting characters. Ultimately, it's your game and your standards. There's no reason you should have to cater to somebody you don't think would be a good fit for your game.
If you want, I can help you out with your game and tell you how I'd handle certain situations or character submissions. Send me a PM if that works!
