The best thing that can be said about the show is that it finds humor in absolutely everything, from babies left in dumpsters to the death of parents. The show is neither for the high-brow nor the weak-stomached. It is, on other hand, far smarter than it may initially appear. It has a distinct point of view, and makes no bones about the fact that the characters are not role models. If one is trying to equate it with other things on TV, the most apt comparison would be that It's Always Sunny in Philadelphia is Seinfeld crossed with South Park. The characters are narcissistic and shallow, make a lot of poop jokes, and yet there actually sometimes seems to be a message or meaning behind it all.
Even so, there are many moments when the show does seem to defer to frat boy humor over a larger meaning or message. These are the times when the viewer feels dirty for ever having turned the show on, and they happen a little too often. By no means do all television programs have to have a message, but if It's Always Sunny in Philadelphia eschews giving an episode meaning, then all it is left with is a couple of off-color jokes about putting a dumpster baby in a tanning bed.
And that is just a little too wrong — not in a good way.