I think I have a pretty good tolerance for shows. I'm the type who's willing to give shows second or third chances, but here are some deal breakers for me.

1. Incestuous Relationships In a Group of Friends
I hate shows in which everyone's slept with everyone else. It's just annoying for me. Don't get lazy, writers. Introduce some new characters! (On a weird note: actual incest is less annoying for me. But that's probably because I've only seen it on good shows.)
Culprit: Gossip Girl (This hookup chart was created a year and a half ago. It's a lot worse than that now.)

2. Storylines Befitting Soap Operas
May or may not include: stalkers, stalker-kidnappers, stalker-murderers, murder cover-ups (done wrong), people coming back from the dead, long lost siblings coming back from the dead, secret affairs, secret love children, etc.
Culprits: One Tree Hill, Gossip Girl

3. Overhypedness
This is more of the fan's fault than the show creators themselves, but it's still a deal breaker for me. When everyone acts treats one show like the savior of primetime television, and I don't get it, I just start feeling left out and confused. And then I give up on the show. And eventually start hating it.
Culprits: Glee, New Girl

4. Procedural Shows with No Overarching Storyline
When a procedural show's episodes don't relate to each other, I see no problem in missing a couple episodes here and there. Next thing you know, I'm missing a full season. And then I let the show go completely.
Culprits: Criminal Minds, Law and Order: SVU

5. Procedural Shows with Complicated Overarching Storylines
This usually happens to keep a show going a few seasons past its due date. Writers start throwing random things into the show to keep things interesting. It just gets too complicated for me.
Culprit: Burn Notice

Source: echofades

How I Met Your Mother: Barney Stinson & Robin Scherbatsky
The writers teased us with a "legendary" season four by putting these two together and then took it away from us the following season. What's up with that? (Cue SNL singing...but I digress). Barney as a womanizer is becoming a tired old routine and I'm glad that they're hinting at him getting married this season. Robin better be the girl at the end of the aisle though because they're clearly awesome together.

Source: vasymollo

Gossip Girl: Dan Humphrey & Blair Waldorf
I admit, I'm a sucker for couples that initially hate each other and then later realize that they have a lot more in common than they realized (e.g. Veronica Mars & Logan Echolls, Haley James & Nathan Scott). I know there are a lot of people who think Blair and Chuck are "endgame" but I really think Dan is a better guy for Blair. Their relationship is a lot more real and it doesn't require games and dramatics. And c'mon, look how adorable the two of them are with their flirty smiles at each other. By the way, why is Prince Louis even still there? The royal wedding storyline is ridiculously unbelievable and does anyone even like Louis?

Source: smoothdog

Hawaii Five-0: Steve McGarrett & Kono Kalakaua
The possibility of this happening is so slim. It doesn't help that a new character has been added to the show as a love interest for Steve. I think Alex O'Loughlin and Grace Park have such great chemistry though. Look at that smile they're giving each other! And the look of concern from Steve at the end of Season 1 when he sees that Kono has been arrested. I think if these two ever get together, I may just die. I don't even need the two of them to date, I'd be satisfied with some flirting between the two of them. Make it happen!