When I search for just about anything there's a few, ok a ton of, porn listings that come up.

I can understand if one of the words I searched coresponded with a word in the porn listing but most DO NOT.

I search my last name, results = a ton of stuff that's porn and is no way has my name in it.

I search for anime/manga/anime songs etc... and mostly the results are porn that matches none of the keywords I put in.

Yes, I know about filtering, I was just wondering why my searches were returning these results when they don't match any of the words I searched for.

look at the filenames for closely. and then also understand that matching queries to filenames then to results can also match by the full path.

There are some hosts out there which return porn to whatever you search. Add those to your block lists.