Paki definitely has a bad connotation... no matter where you are....but not desi....
And tbh, i hadn't even heard of the terms 'abcd' and 'fob' till i came to GS :D
I don't think saying someone is pakistani is considered bad in the US, well atleast not in NY, then again NY is a world of its own!
The only term I consider bad is FOB.