"X is a reference to Y"
"X may be a reference to Y"
"X is inspired by / is most likely inspired by / might be inspired by Y"
Personally I find this kind of statement should be more strictly policed. For example, they should require something like a quote from a Rioter to be valid. Something being similar to something else seems uneccesary unless it has been right out stated in a Q&A or something. Trivia should deal with facts and not subjective associations. Even the blatantly obvious references, I think, are pointless to list. I would be okay with maybe one general "looks like X" per skin, but would personally rather have none unless properly referenced.
The alternative is trivia sections fifty rows long with movies, games and characters, obscure and mainstream, that people are reminded of when they see a particular skin or whatnot. I don't think that is a good use of the Trivia section. The use of references and citation on the wiki is often lacking but especially bad on the trivia sections. Is it okay to just go in and clean up the Trivia sections where it's needed?
Edit: For an example, just look at Rengar's Trivia section.
Edit2: Okay, I've gotten the impression im not the only one who feel this way about Trivia, but it might be a bad idea to police it, still. How about adding a new section with properly quoted and organized facts? Called, lets say, the "Notes"-section or something? That way you can have referenced material that content are actually based on separate from the "X reminds me of Y"-stuff. How about it?