My wife and I like to go to open houses on the weekends - in my own neighborhood and in the San Francisco Bay Area, where my parents live. Lately, I've been really disappointed with the tremendous lack of knowledge shown by so many real estate agents; it's as if they don't believe that the buyers and sellers find the provenance of a home and its architectural tradition important criteria. I was lucky enough to buy my home from an agent here in Sacramento who specializes exclusively in older Craftsman and California Mission bungalows in our neighborhood, but many people are not so lucky: in a volatile market, you get agents buying and selling themselves, doing just as much damage to old finishes and materials as any casual flipper interested only in flash.
I've heard agents counsel prospective buyers that beautiful red oak interior trim would be "livened up by a coat of varithane," or that "those old lathe walls really hold the heat - it'd be much more energy efficient to put in vinyl windows and replace some of this interior wall with sheetrock." One agent, within earshot of a seller obviously very attached to her immaculately restored 1919 brown shingle Western Stick home, asked a visiting couple if they'd thought which walls they'd tear down now that they didn't need two small bedrooms for their kids any longer, and suggested a bearing wall heavily ornamented with sculpted plaster moulding and mahogany wainscoting that must have taken years to strip, sand and refinish. Still more agents have suggested using colored mylar to create a stained-glass effect in a 1909 Spanish Revival home, replacing beautifully-maintained period linoleum with laminate, and covering hardwood floors with carpeting.
Real estate agents: wake up! People who buy old houses buy them for a reason, and it is not sentimentality. They appreciate a higher-quality construction that you don't often find in postwar homes, and they know what they want and they know how it should look. Educate yourselves a bit more - learn a bit about the local architectural tradition, and don't rely on what you've picked up by osmosis to sell houses. You may be only in it for the money, but you are the guardians of your own town's architectural heritage.
In architecturally-rich communities like the Bay Area, Portland Oregon, Pasadena and Los Angeles and to a lesser extent the urban neighborhoods and suburbs of Chicago, agents are by necessity as well-trained in architectural and design history as most undergraduate architecture or interior design students. However, this is the exception and not the rule, and you're going to need to do a bit of work to match the knowledge of many of today's well-educated buyers. There are dozens of good books on the subject out there; any good primer on residential home styles is the best starting place, probably, with books like Powell and Svendsen's Bungalow series (bathrooms, kitchens, etc.) or Teena Crochet's Bungalow Style also very useful.
Visit the local architectural salvage yards and check out the premium that all those discareded pieces are being sold at. Refuse to deal with flippers and the tear-down set. Cultivate friendships with cabinetmakers and handymen who appreciate old houses. Know the important architects of the area, the reasons behind neighborhood names, and why, for example, one shouldn't put a huge mock-tudor in the middle of a neighborhood full of modest shingled bungalows. If you appreciate good taste, you'll attract clients who have it as well. Your new mantra will be "why paint when you can refinish? why cover when you can restore? why remove when you can improve?," and eventually you will earn a reputation for sensitivity, knowledge and compassion to homes, buyers and sellers.