The only thing I outright didn't want to continue after one episode was Zettai Karen Children. Oh, and Penguin Musume Heart, holy shit that sucked.
The rest I'll give a few more episodes - at least 4, before I'll pass judgment.
Of those, the iffy ones are:
Special A - ep 1 was ok, 2 was DISGUSTING. Heard good things about 3 and it's sitting on my HDD waiting to be watched.
Wagaya no Oinari-sama - dunno, just doesn't click with me
Amatsuki - I like it, I just want to know what the fuck is going on.
Nabari no Ou - GRHGRHG fight quality in 3 dropped to beyond shit, compared to ep 1 which was impressive and ep 2 which was decent enough.