While I don't agree that it denotes bad UX in all cases, I acknowledge that it can be overdone to the point of annoyance (ala the new YouTube, which is a hover-fest)
I have to say I quite like YouTubes latest incarnation with all the hover elements because I have no interest in using anything other than the play button (I only use it for listening to live versions of music) and so a cleaner "first impression" UI suits my persona very well.
I understand that it can be a horrible experience for a persona which is specified to be 'low-tech knoweldge high-functionality use' though.