QUESTION: "Should I try to enforce a "pre-qualified buyers only" requirement on my listings? If so, how?"
JA's ANSWER: Every once in awhile I'll hear an agent say that he (or she) restricts showings on his listings only to buyers who are already pre-qualified for the purchase price. His rationale is that it's inappropriate to inconvenience a seller by allowing showings to buyers who in all likelihood cannot or will not purchase the property.
I disagree - I think it's simply a matter of setting appropriate expectations with a seller. In 12 years, I have never had a seller ask me to screen buyer showings, probably because I warn them upfront I have no control over who looks at their home. Some will be real buyers, some will be agents previewing the competition for their upcoming listing and some will be buyers out for the first time who won't buy for six months.
"However," I continue, "any activity is good activity, even if it doesn't result in a sale, because the home has been exposed to one more (actually probably two or three more counting the Realtor & buyers) and exposure is always a good thing. We should do everything we can to encourage showings, rather than look for ways to trim them down. I'd much rather risk your being a bit inconvenienced by lookie-loo's than miss a previously lukewarm buyer who suddenly turns into a red-hot one."
My sellers ALWAYS say - "Of course! We want as many people as possible to look at our home!"
As a wise (wo)man once said... "Unseen is Unsold!"