In order to max out the Beauty condition of a Feebass that doesn't like dry Pokéblocks, the level of the Pokéblocks will have to be more than 10/9 times more than the feel. (assuming my memory is correct that Pokéblocks of a disliked flavor increase the level of that attribute by 0.9 as normal) For example: level 25, feel 20 blue (or other colored mostly dry) Pokéblocks should work.
But after you max its beauty out, I don't see why it wouldn't evolve, even if it hates dry flavors.