Ah, some honesty.
Those examples suck, but I wouldn't say graphic t-shirts or graphic hoodies in general necessarily must suck. There are some that would be okay by me. I'm not a big wearer of them myself, but some I could abide.
Clothing/style says a lot about who you are, or who you want people to think you are. If you want people to think you are dressed by a 2nd-rate sorority girlfriend, then the above kind of thing would be correct for that look. (Refer above to Rye's "douche" point.) If you want to say "I have a rudimentary understanding of the trends in current, local, popular media and a willingness to pay for it" (not necessarily such an unwise viewpoint, esp. if you are dressing "to be attractive to women") then go buy everything GQ tells you. If you want to say something else, you'll need to figure out what that is, and then go about figuring out how to say it.
Some of us are saying "I think so much about clothes/style/whatever that I don't even care what 99% of people think I look like". Some are saying "I just want to fit. in. [with a conservative business crowd, or my douchey peers, etc.]". Some say "I can afford to buy overpriced concept pieces and can get away with wearing them out of the house". There are as many styles and style statements as there are people (who care at all). The thing is to find one that represents you, so that you can be comfortable in what you're wearing, and not be worrying about it.
Only when you are comfortable in your clothes can you forget them and concentrate on what is important in front of you, and be attractive. Ironically, this is why people who genuinely don't care about how they look, and dress accordingly, can still do surprisingly well in the social game.
So what am I saying? Stop caring completely, and dress from Wal Mart? Maybe. I dunno. Hopefully I made some sense.