I think there's a huge difference between unlikeable, and engaging in the proper sense. I think Scarlett O'Hara's a classic example of the unlikeable but engaging, and I suspect it's because she behaves in forceful, selfish ways that women, in particular, are trained not to do: it's like cheering on the vengeful dumped women who do terrible things to their ex's suits or whatever, even tho' we'd never do such things ourselves. (Would we?
). Cathartic, that's the word I want. You identify with her to that extent, while thinking she's behaving badly. Whereas as someone said (sorry, only skimmed the thread) the whingey feeble type of unlikeable isn't something most of us would like to be, or identify with.
If you say someone's 'likeable' in real life it does always sound like damning with faint praise, but in fiction I don't think 'likeable' need just be fluffy or saintly or boring. 'Care-about-able' might be a better word.
But I also think
Comprendre tout c'est pardoner tout (sorry, probably spelt that wrong) and so you can make just about any character engaging for at least some readers, if there's a really organic sense of how and why they're like that.
But just as some people love having edgy, disturbing Expressionist pictures hung at angles on their walls, and others magnificent, grand Classical images carefully balanced and spaced, you're always going to get a range of tastes on this one, because it is about taste.
Emma