I do know at least one case of really good show saddled with a terrible theme song, though. I just finished the first disc of Shout Factory's recent season 1 "The Paper Chase" release, and, hoo, boy, does it offer a stinker.
The series itself is quality entertainment, and I look forward to seeing the rest of this and of future seasons. But that Gimbel and Fox (who also brought us the theme from "Happy Days") theme song almost wrecks the whole enterprise. In fact, it might have done just that for me, but fortunately the pilot holds it until the end. Thus, I enjoyed the first episode without having that wretched number clouding my judgment of more important things like the writing, the acting, etc. When it DID come, though, I burst out laughing and actually forgot I had been watching the real "Paper Chase" pilot. The combination of the classic freeze frame and the onset of Seals and Crofts suggested I was watching a parody. I had to double-check to ensure I hadn't somehow put an "SCTV" episode in the player.
The first years are hard years
Much more than you know
With good friends to love us
We'll field every blow
Don't get me wrong, I like a solid dose of sentiment every now and then, and indeed much of the appeal of "The Paper Chase" is in the warmth of the interpersonal relationships and the sincere, heartfelt tone of the series. But these lyrics are laying it on a bit thick.
I'll spare you the second verse because you're not really getting the full effect, anyway, unless you hear the song as performed by Seals and Crofts in its twee glory. If you have a song with sappy lyrics but you want to avoid complete sappiness, I think the last thing you should do is bring in Seals and Crofts to perform it.
The producers of "The Paper Chase" saw this differently.
As I said, avoiding the song till the end of the episode in the pilot gave me a chance to appreciate this comedy-drama as one of the better series of its time. Had I watched one of the other episodes on disc 1 first, who knows? I don't _think_ the theme song would have spoiled the whole series for me, but I'm glad it didn't get the opportunity.