It's easy to pick on the colonials, let's taste our own bitter medicine.
n.b. these are "over rated" sitcoms, e.g. rated to highly not inherently bad.
1 'Allo 'Allo!, the same joke repeated ad finitum.
2 Last of the Summer Wine, old people not being funny.
3 Only Fools and Horses, it's just sort of dull and nothing much happens funny or otherwise.
4 Absolutely Fabulous, ran out of steam early on. Being drunk and shouting isn't funny on it's own. (Yeh I know that's 4; so sue me.)
I didn't include 2 Pints because I don't think any one rates it that much.