Personally, I'd say that once you reach a certain age or understanding of music, a dislike of someone shouldn't be labeled as 'controversial'. To beat the dead horse some more...look at Marilyn Manson. Loved...L O V E D his earlier stuff but he let himself go and his work has blatantly suffered as result of it. Can't stand him now and often wonder how I could at one point. I chalk it up to being a teenager though, and am grateful that it was a gateway of sorts to better music.
Personally I can't stand Limp Bizkit but am fully aware that some people do. I always found the 'bro rock' bands to be cliche as hell but whatever floats your boat. Agreed on Slayer. Whereas I wouldn't say they're overrated, I can probably get through about 2 songs max before switching to something else. Also agreed on Iron Maiden. I get what they've done for metal but I can't get in to them.