Use 'distasteful' for things that upset your physical senses, especially taste and smell. The distasteful aroma from the decaying plant made me leave the room.
Pro Tip 2/3
Metaphoric Usage
'Distasteful' can metaphorically describe something that 'leaves a bad taste' emotionally or intellectually, not literally. The conversation about the accident was so distasteful that I didn't want to continue.
Pro Tip 3/3
Intensity Matters
'Distasteful' is milder than 'disgusting' or 'revolting' but more serious than 'unpleasant'. The movie had a couple of distasteful scenes, but it was not enough to make me stop watching.