Yes, there have been some really dire songs over the generations, and that's fine if everyone agrees that they are awful.
But I think that what Ewan was getting at (correct me if I'm wrong, Ewan), is when some people use very hyperbolic or expletive language in their condemnation of a particular song they don't happen to like (but maybe many others do) - and furthermore, go on to condemn those who do profess to like said song, as being mad, tasteless or otherwise deficient.
It IS down to personal taste at the end of the day, isn't it, even with those songs that "cross boundaries" or use intense black humour which may offend some?