When I was pregnant I almost bought my son a onesie that said "I love my mommy even though she's a bitch."
I waited about getting it. Then in the mall I saw a baby with a shirt on that said something about "yelling and mommy popping her tits out." And I just hated it for some reason. The saying are cute until you put them on a baby. So I agree @princessmommy
And as she said, this is my opinion.
They don't know what anything says so should they not wear any clothing with text? Not trying to be rude but as long as it's not in completely bad taste I think it's ok.