After the ''recent market disturbance,'' as stock market newsletters never fail to describe events such as Oct. 13, brokerage houses were busily reassuring shell- shocked investors that, over time, stocks still offer the best returns of any investment.

Readers of my own confidential tipsheet, the Efficient Market Theorist, will know this is hogwash. If you want to make substantial returns on your money, year-in, year-out, there is really only one sector to invest in: oils. Impressionist oils, that is.

Stocks have historically gained on average about 10% yearly. Over the last 15 years, your average Salon reject has climbed in price at better than 20% a year. In the last two years, the Impressionist market jumped 150%, and the big New York auctions this month confirmed the trend.

Granted, this may appear to present some barriers to the small investor. But innovative new financing techniques are drawing the glamorous world of the auction house within reach of even the most impoverished investors. Just ask Alan Bond.

The Australian tycoon's purchase of Vincent van Gogh's ''Irises'' for US$53.9 million (C$62.9 million) in November 1987 - still a record for any painting - raised high brows to begin with. But this was nothing like the reaction accompanying the news that Sotheby's, the international auction house handling the sale, had loaned him half the money.

SCANDALIZED ART WORLD

The combination of skyrocketing prices and auction house manoeuvring has scandalized the art world, much as junk bonds, program trading, and the ''recent market disturbances'' have all been popularly lumped together as so much ''casino capitalism'' on Wall Street. Time magazine art critic Robert Hughes might call it ''the shock of the new.''

He might call it that, were he not one of the leading members of the Salon of financial orthodoxy blaming Sotheby's and its rival, Christie's, for the price explosion, which he argues is shutting public museums out of contention for works coming onto market.

The aggressive new financial methods have allegedly puffed up the market with extra liquidity, and given the auction houses a direct interest in overstating the condition and importance of certain pieces.

The first thing to note is these are in fact not new at all, except perhaps to the art world. The notorious advance to Bond is nothing more than a bridge loan, familiar to financial markets. Likewise, Sotheby's agreement to guarantee the John T. Dorrance estate US$110 million on sale of its collection is simply a variant of the ''bought deal.''

The second point is that this is largely a self-correcting problem. Christie's has invited special scorn for making overly optimistic estimates of what it thought it could elicit for 14 of the collector Paul Mellon's paintings and sculptures. It got the nod over Sotheby's more conservative appraisal - but sold only half the lot. Sotheby's, by contrast, set a new single auction sales record the next night. Other sellers will have noted this, and will take the path of caution in future.

The third point is that it's not clear there's even a problem. Most of the critics of the auction houses are art dealers - their direct competitors and, until a few years ago, their main customers.

One detects more than a hint of snobbish disdain for those arrivistes, especially from Japan, who have dared to soil the temple of art with their vulgar wads of cash. Maybe they have pushed the bidding beyond the museums' reach. But museums can't bid at all on something that's not for sale. And if Sotheby's and Christie's were somehow prevented from offering greater assurance to sellers, either by providing loans to buyers or guaranteeing prices, the market would dry up. Perhaps that would encourage more collectors simply to donate the pieces to museums. Perhaps not.

Museums, don't forget, can sell into this market, too. If their hearts are set on a masterpiece, why shouldn't they sell off some lesser works to finance it? For that matter, one of the effects of the bought deal, was to let some paintings go for less than they might otherwise. Since Sotheby's had guaranteed a price for the whole lot, rather than for each individual painting, it had an incentive to take whatever it could get for them, instead of insisting on a minimum ''reserve price.''

If Hughes and other critics want a villain in this piece, they would be better advised to look at U.S. monetary policy, the real source of the liquidity, fueling the rapid rise in asset prices of recent years. Art critics for a sound dollar?