Re Frank, since most of his scams backfire one way or another, while his getting a slap on the wrist back in the day because of racism might have made me feel sorry for him if he had stayed clean since then, but Frank being Frank he's not only ruined his own life, he's dragged his kids down with him, so I've got no sympathy for him.
Re Kev & Veronica, since the only reason they're still in business is because they crashed an AA meeting, I don't have much sympathy for them, either.
Re Liam & Debbie, bore, rinse, repeat.
Nowadays,Lip & Ian are the only Gallagher kids I care about. Lip & Tami have their problems as parents, but at least they're trying, in their own way, unlike Frank. As for Ian, while I agree that Ian shouldn't get married for the wrong reasons, IMO it was Mickey who went too far. I don't care how hurt Mickey was, he shouldn't have hit Ian. As far as I'm concerned, being hurt isn't a license to hurt others.