I believe that, under all that malevolence - and Q was malevolent - there was something about Humanity and Human Beings that interested and attracted him
Cruel, yes. Malevolent, no. The kind of cruelty that is easy to pick up (I suppose) if you've been (almost) omnipotent for aeons.
I'd consider Q more of an 'amoral trickster' as someone else put it, and even then he might only appear
amoral in our eyes . Most of the time Q does anything, it ultimately seems to have a good effect on the main characters or the Federation as a whole, even when the acts seem "evil" at the time itself (Q who, tapestry). Of course, we're led to believe that this is because 'our heroes' made the best of it, but I always got the feeling that this was the intention of Q all along. Picard with his 'holier than thou' attitude, for example, really could use the kick in the rear he got from Q every now and then. Of course, that doesn't explain all his evil acts away, such as 'tormenting the Calamarain', but still.
Well, that is considering the TNG Q at least. When VOY Q came along, I really got the feeling we were dealing with a supposedly omnipotent entity who didn't actually have the slightest clue as to what he was doing. In that respect, VOY spoiled Q for me, even though he was still fun to watch in those eps.