I almost cracked up the other day when I read somewhere that the average homebuyer sees 12 houses before buying one. I suppose that's simply one more way in which the San Francisco Bay Area real estate market differs from much of the country. In fact, I know buyers who have seen 25, 50, even 90 houses before they buy "the one."
Most often, it's not because the buyer is overly picky, but because they've made offer after offer, and been overbid or (more often) bested by buyers paying with all cash or higher downpayments time and time again. Or, they got into contract on a house or two, and had the deal fall apart because the place turned out to need a new foundation, or some such.