Huge 24 fan here (watched all seasons), I loved the show but that doesn't mean I support torture. I always found the following things ridiculous (and pretty unrealistic):

1) The ridiculous urgency of it, where they're running against the clock to "stop the bomb" or something like that. These kinds of scenarios are highly unlikely in real life, IMHO.

2) That Jack Bauer always got away with all the things he did. AFAIK, he did not spend even a single second inside a US prison (although he did come pretty close a few times).

I always looked at the show as fiction (like a superhero show), not something to be emulated in real life. I really hope most of its viewers looked at it the same way.