Electric guitar is a bad instrument and should never be used. (In fact, that instrument gives me headaches, which means I often can't listen to music that contains it.)
Non-melodic percussion should be used sparingly; it should be used as an accent or color, and there should not be a constant drum beat. (Rule of thumb: Can one easily play a C major scale on a percussion instrument? If you can, it's melodic, otherwise it's not. Rule might not necessarily work for non-western folk instruments.)
In concert band music, brass, particularly trumpets, should be used sparingly. For example, trumpets should not be given the melody unless it's a climactic point in the piece, or if one wants a specific color at a specific point.
This might sound ridiculous, but I actually enjoy the clarinet's altissimo register. Those pitched squeaks are fun to play. (By the way, I think "pitched squeaks" is actually a good term for it.)
More people should take up oboe and bassoon; they're nice instruments. (It's too bad they're quite expensive.)
teceem: I like Tiga's remix/cover better than Corey Hart's original.
--- Just post what pops up into you mind, don't take the topic's title too seriously! ---
grimlock047: Mine: Things like rap and dubstep are not "music". Also don't know those songs mentioned above but I'm pretty sure they go into my "not really music" category
What would you say about the works of John Cage? Is his famous work 4'33" music? (He claims it is, I believe, but this question has been debated by musicologists.)
teceem: But here's a guess... you don't like music with electronic instruments? And that would be perfectly fine... I'm not here to judge!
In my case, it's certain electronic sounds, like the electric guitar, that I have a problem with.
8-bit chiptunes are not an issue for me (though I don't like it when there's constant percussion, especially when it comes at the expense of harmony or counterpoint), but 16-bit tunes can sometimes cause issues, at least when they start to mimic the electric guitar. (Comix Zone's soundtrack is one offender here.)
NES music is better than Sega Genesis muisc, as far as the instruments are concerned. (This is independent of how well the music is composed; it wouldn't be hard to find an NES game with worse music than Phantasy Star 4, for example.)
Final Fantasy has a good soundtrack with many great tracks; Battle on the Big Bridge is not one of them. (With that said, the FF12 orchestral remake of that particular tune is good.)