One way to weed out some of the lookers is to require proof of funding. ( Bank statements , non IRA / 401 investments. )

Another way is to go over the ad in detail with the person over the phone. I see this with general Craigslist ads where the caller never reads the ad.

If the house is dated, they should be looking at those new but cheaply built houses in a plan. Next will come the cries that there is a ( non critical ) crack in the wall, at that point I'd say "You are buying the house as you see it, if it does not meet your requirements, move on." . I'd hardly call 89 old, just be sure anything that a bank loan agent would kick for repairs is complete, ( hand rails, peeling paint and such )

My Mom and Dads house was built in 34 , I recently had an appraisal done and the 30 something real estate guy only cared about updates. The roof was 2 months old, HVAC 10 years, modern electrical service, neutral kitchen from mid 80's. I don't know that much else can be updated. The person buying this house will want if for the 30's character not if it has SS appliances.

It is a nice neat clean effectively 2 owner house, putting in a stainless kitchen would be out of character as would removing the tile bathroom and period fixtures. ( It was built by a young couple that lost it after a year,the next people had it until 2000 when Mom Dad bought it. )