Is there some way for the search results to be filtered by the "rating" and not just the "tags"? To my mind the existence of a rating system indicates that the "safe/questionable/explicit" rating is a filterable aspect, otherwise why waste the coding time building the system.
So how does one actually take avantage of the rating system?

Do you mean filtering by rating,or sorting/grouping by rating?

There's the rating:* query,where '*' could be s,q or e for safe,questionable & explicit respectively

um, rating:safe, rating:questionable, rating:explicit ????

Search for a rating by using either rating:e, rating:q, or rating:s. Filter out ratings by using -rating:e, -rating:q, and -rating:s. Full words work too, like rating:questionable.