It depends which Sorting Hat song you read.

Said Slytherin, 'We'll teach just those
Whose ancestry is purest.'
Said Ravenclaw, 'We'll teach those whose
Inteligence is surest.'
Said Gryffindor, 'We'll teach all those
With brave deeds to their name,'
Said Hufflepuff, 'I'll teach the lot
And treat them just the same.'
- from The Order of the Phoenix

Hufflepuff is a catch-all house. Helga would teach all of those who didn't fit in a particular house - hence Zacharias Smith who doesn't seem loyal either. Basically Crouch snr (and jnr too) could have fitted in any house. I still cannot see either of them in Gryffindor, despite me knowing that a few Gryffs are not that great (McLaggan, Vane, Pettigrew), but the Azkaban plot you advocate as brave and reckless was meticulously planned and only agreed to because of the devotion he had to his wife. This screams Ravenclaw or Slytherin. But he's a hard worker, we understand that much from Percy and Ludo, so Hufflepuff fits there too.
What strikes me is his fanaticism and rigid attention to detail (personal and otherwise). It seems very un-Gryfflike and I still maintain that it wasn't bravery that made him seek out Dumbledore, but a sense that it was the only thing he could do to stop the situation.

The Crouch family are described as an old pure-blood family by the way, and there's one or two of them featured on the Black Family Tree.

Back to Barty Crouch jnr (which is the title of the thread - sorry mods, I've drifted); is there canon evidence that he was a Slytherin? Although I've always placed him in Slytherin, I can't remember if that's canon or fanon.

Barty jnr seems to have been closer to his mother than his father, so do you think she would have been sympathetic to Voldemort's ideals, or would she have been more allied to her husband?