HERE'S the latest product being pitched door-to-door in ecologically minded Seattle: An all-purpose cleaning product that the salesman claims works wonders on dirt without harming the environment.
After tasting some of the product to show how harmless it is (in diluted form), he reveals the ''best'' news: The highly concentrated product is ''just'' $30 for a one-quart bottle. As the homeowner recoils with sticker shock, the salesman insists that this is about what the average household spends monthly on various cleaning products.
Across the country, more and more products are being marketed as environmentally benign, though this hard-sell approach is unusual.
But how much weight should consumers give to a product's environmental impact? Are products marketed as ''green'' significantly less harmful? How do they rate in terms of price and performance?
The answers depend not only on the product but also on consumers' priorities. (A family with young children may stress avoiding strong chemicals, for example.)
Some experts don't see much difference in environmental impact among laundry detergents, for example. Mainstream products have not contained phosphates for years, as many states ban the algae-growth-promoting chemicals. Procter & Gamble's Tide now comes in a recycled-plastic bottle.
Philip Dickey, who researches household products for the Washington Toxics Coalition in Seattle, says laundry detergents are ''more and more the same.'' In a guidebook he developed last year that rates household products on environmental, health, and safety issues, he doesn't bother rating detergents.
Yet Jeffrey Hollender can offer reasons why consumers should buy his laundry detergent. Seventh Generation's product is vegetable-based, Mr. Hollender says, and Americans could save 364,000 barrels of oil a year if each household used one bottle of his detergent instead of a traditional brand.
For most consumers, environmental issues rank far lower than such concerns as price and brand-loyalty, according to a survey by Roper Starch Worldwide, a New York research firm. In 1994, fewer Americans (17 percent) said they shopped environmentally than did respondents in 1991 (25 percent).
Consumers take environmental issues most into account when they decide which household cleaner or lawn and garden product to buy.
Environmentalists say it will be hard to know how strong the demand is for Earth-friendly products until more are available alongside their rivals in supermarkets.
Makers of traditional products, meanwhile, say there's a reason the alternative products haven't made it into the big time: They don't work as well. Studies in Consumer Reports magazine have found a number of so-called ''green'' products are more costly and less effective than their counterparts. But it some cases, ''not as good'' is still good enough, and the products' weak track record may be improving.
After revamping its products to perform better and cost less, Seventh Generation has made inroads into supermarkets (Star Market and A&P in the Northeast, and Larry's in the Seattle). The Colchester, Vt., company also sells by mail.
For green products, winning market share means not only being competitive in price and performance, but also convincing consumers that leading brands are bad.
''Nobody can ever say what's wrong with these products,'' says Sandy Sullivan, a spokeswoman for the Clorox Company in San Francisco. A recent ad for Clorox bleach notes that the product ''breaks down to little more than salt and water'' after disposal. (Dickey says this is correct but is suspicious about what ''little more'' includes.)
In his product-rating guide, Dickey is more pragmatic than dogmatic. He does not recommend specific products, but provides a rating in four categories: acute toxicity (from ingestion, breathing, or skin contact); chronic toxicity (from long or repeated exposure); flammability or chemical reactivity; and environmental impact (biodegradability, toxicity to fish, etc.). Consumers must judge price and performance for themselves.
Where many environmentalists focus on make-it-yourself recipes, Dickey says most people find homemade cleaning concoctions a nuisance. But he also warns about commercial products. Not all cleaners that claim to be green really are, he says. Looking at literature about the $30-a-quart cleaner being sold door-to-door, he notes that the ingredients aren't listed and the price is high for an introductory product.
The area where people can make the biggest difference on the environmental front, Dickey says, is in pest control. In the garden and inside the home, he says, mousetraps, fly-swatters, and storing food properly often succeed, making the use of toxic chemicals a ''last resort.''
Also on his black list are corrosive products used to clean drains, ovens, and toilets. He prefers solutions such as the use of plungers and snakes in drains and the noncaustic version of Easy Off oven cleaner. Dickey applauds S.C. Johnson for its Toilet Duck cleaner. ''Now, if they would just stop making Vanish,'' he muses.