I just moved to Houston last month!
Listing
#1 I would suspect immediately because they didn't actually post pics of the bike. offering to text pics means the person is either a) too lazy and is probably pretty flaky, or b) the bike is in rough shape and the crappy txt pics won't show that so he's trying to sucker someone over. If it's in decent shape, I'd offer $250-300.
#2 i don't know a lot about carbon bikes at all. someone else might be able to help you with that. if it's truly in good shape, i'd say the price is alright, maybe high for an 8 year old bike.
#3 needs to be cleaned, and to me it looks like the tires are flat. i'd want to know what year it is and see it's real condition before talking about $700 being too high or low.