I give them lots of foam. It's the cheapest function next to rinse, and there's no reason to be stingy with it. Our only competition has their foam brush so thick that you only get a small puff of foam every ten seconds or so, and I love it because I know it won't
soap up a car.
I've had only one person comment negatively on the fact that it puts out so much foam, and when I told him that I have it that way so the people who use the foam brush first on a dry car will do less damage, he understood completely. But I also have it extra rich so they'll spend more to rinse it off.
I agree with the perception of value too. Give them more than they expect for their money whenever you can. We're probably the only ones anywhere that give more than a minute for a buck on the fragrance machine, and I never see customers throw down the gun like they got ripped off. I see that all the time at washes that give only 40 seconds, even for 75?. I even watched a poor guy once who deposited his 75?, went to his car
door and it was locked, fumbled for his keys and got the
door open, then finally found the trigger on the gun just as the time ran out, and what did he do? Threw the gun on the ground and left. At our wash he still would've had 30 seconds left. He likely wouldn't have realized that my generosity allowed him to get some use out of his money spent, but he wouldn't have left mad. Not only that, if he uses our competitor's fragrance next time, he would feel ripped off.