How to automatically fix MP3 Genre and Year tags?

All the Artist/Album tags on my MP3 collection are fine, but the Genres and Year tags are all horrendous.

For Genre, songs just seem to be all over the place. It classifies Iron Maiden is Alternative, Ozzy as Oldies, and Pink Floyd as Pop.

Year is even worse, because Amazon always seems to use the "remastered" year instead of the year the actual album came out. For example, it tags my Led Zeppelin albums as coming out in 1990+.

Is there any program that, assuming the artist and album is already correct, will automatically fix the Genre and Year tags?

If you are satisfied with the data in the MusicBrainz database, you could use MusicBrainz Picard (FLOSS and cross-platform) to retag your collection automatically.

Regarding your two examples:

I don’t know how widespread they are, but I use the metatags date and originaldate to differentiate between actual release date and original release date.

As genre is most often subjective, I don’t use this metatag at all.

As it was said above, the Genre is really subjective so there may not be an automated way to tag mp3s with genres. One could possibly use a Discogs-enabled application for this, but do bear in mind that the online database is often ambiguous on the genre matter. Take for example the Lycantropy album by Patrick Wolf. Here, Discogs provides two entries for "style" ("IDM, Synthpop") and, moreover, it labels the "genre" simply as "Electronic". As for the year, Discogs can list more than one year for an album when it was reissued a number of times. Still, there is an automated mp3 tagger program called taghycardia that can supply a best-guess on the year missing from a tag, although only when the tag lacks more crucial info like album or artist.