I thought Sanctuary was a terrible show, and yet I still watched every episode.
The things that annoyed me the most was that they called the monsters "Abnormals" despite the show claiming that they were natural and normal. Maybe it's just me but calling them "Abnormals" is worse than simply calling them monsters. But the thing that annoyed me more than anything else, was how the Cabal (I think that's how you write their name), which were hyped up to be a big evil organisation and the main villain for season 1, were completely destroyed off screen, early on in the next season.
The show definitely got better as the seasons went by, but I have no idea why I kept watching it.
I'm not sure what show to put up, so I'll just choose something that I'm currently watching, and see if anyone can guess it.