From the FAQ, AKA "Newcomers Guide" which is the last thing any newcomers read:

Explicit Lyrics: Some people have suggested that there should be a warning posted at the beginning of threads that include lyrics that are sexually explicit. Bawdy songs have always been an integral part of folk music, and you'll find lots of dirty ditties if you do a category search of our database for @bawdy. There is no set policy on this sort of thing, but Standard Mudcat Policy is that freedom of expression is to be encouraged and protected. If you're going to post something spicy and think you should label it, that's fine - but there is no requirement for labeling here and visitors are advised that they read at their own risk.

I do agree that it would be best if the searches here found the specific song you're looking for first, instead of parodies, but that's an accuracy issue. (And Max is working on it, I believe.)

The problem with identifying lyrics not suitable for kids as Edmund pointed out, is definitions of what's suitable and what isn't are extremely subjective. SingSing/Susan may not want lyrics with pubic hair in them. Some else doesn't want rape or people getting killed, and another may object to any mention of one or all religions.

There may be a way to filter out by key words, but I don't know it. ("NOT @bawdy" ??)