Phone a friend
If you're looking for property on your own, see if you can rope in an inspection companion. If your partner can't make it, take a mate along. Share the good, commiserate on the frustrating. Sanity check your impressions and opinions. Working with someone else can offer you a sound board, not to mention a friendly face to travel from property A to B with. It'll also let you try some of these other tricks.
Allow one veto in residence
Each person in your group gets one veto on each day of the inspections, but there's a catch. You can only veto a place if you're actually standing inside it. Which means that you have to hate the place so much that you're willing to use your one veto on it right there and then. You have to be totally convinced that nothing else that day will be as horrible as what you're currently looking at, and you can't save it up for later in the day. It raises the stakes of everyone's input and prevents your party as a whole from being too fussy.
Play house search spies
Create a secret language so you can communicate with your fellow house searchers without the real estate agent catching on. Rubbing your nose = interested. Tugging your left ear = this place is the doorway to hell. Twirling your hair around your finger = the real estate agent is ridiculously good looking. Not only is it hilarious, it's also a fantastic way to keep each other in the loop while maintaining a cool facade. Especially if you're planning on negotiating.
Wear your best clothes
Pretend like you're meeting your significant other's parents for the first time. Who would you dress like? A demure librarian in glasses and a button down shirt? A straight laced accountant in a pin striped suit? Of course you should be yourself at inspections (especially rental inspections), but it's fun to be your very best self. Think pearls and a perfect manicure for the ladies and a natty little bow tie for the gents. You could even go for cocktails afterwards to reward yourselves for a hard day of house hunting.
Dramatise the competition
When crowds of people are hanging around the door of a rental property waiting for the real estate agent to open the doors, take a few seconds to subtly check out the competition and determine who is your biggest threat.
Creating a back story is a silly little way of coping with the disappointment of rejection we all face when house hunting. Then when you finally get your dream place you can celebrate because you beat George the personal trainer and his partner Alex who owns a jazz bar. That'll show you George...
You could break the day up with a picnic or set a reward like watching a movie when you're finished. Even just having a positive attitude can make the world of difference on a long day of house hunting. And don't underestimate the power of a good coffee to get you through the last few afternoon showings.