One thing my parents taught me when I was young and we moved around a lot, is that you shouldn't show interest in a house you're only looking at. That's not to say that you should act uninterested, just indifferent. Don't ooh and ahh over details, just make a note of them. Bring a friend, make sure that both you AND your spouse look at each house in person. One of you might see something that the other doesn't. Check every nook and cranny; you'd be surprised what some dishonest people will try to cover up.
Good luck house hunting