The judges nitpicked what Ricky Whittle did too, and there were no Cliftons in sight when he was around. Good dancers get over-judged just so that it looks like they're still getting critiqued. They're obv not getting judged like the lesser dancers, so they get criticism that is more singular to them, whereas the lesser dancers get very similar comments that aim to encourage at the same time. The judges motivate better dancers in different ways, as it makes no sense to use the same level or type of critique with them.
People constantly go on about a Clifton or Kevin being pushed for a win or being favoured, but never give any reason as to why this is the case. None of them have won the show, so it's not like we or the BBC even know if they're overly popular with the public. Kevin has had three decent dancers and one okay dancer (Susannah was never actually good). Joanne had Scott Mills on her previous occasion (one of Strictly's worst dancers in history) and Karen has had an array of abilities to teach, Dave (Hairy Biker), Nicky, Jeremy, Mark Wright and then Will (who was the best of the lot by far, not even Mark Wright would have been equal to him).
Yes, Kevin hasn't had an older lady or an awful younger lady to dance with, but it's hardly his fault, and it's not like him winning is going to suddenly affect the popularity or positioning of Strictly in terms of viewers or TV survival. What do people actually think a Clifton win will do so much that the BBC would be pushing for it.