'You can't tell the difference!" an art forger gleefully declares in "The Late Christopher Bean," when a supposedly learned dealer examines with uncertainty what we know to be the real thing. The mysteries of avant garde art, where the legacies of a drunken handyman can suddenly be declared immortal -- and hence immediately valuable -- by the New York art establishment, is one of the chief jokes of this dreary play. But apparently it's just as difficult for some people to distinguish quality in devant garde work. Since theatrical revivals of less- than-classic work became fashionable a few years ago, there have been numerous instances in which the mediocre has been handled with indiscriminate respect. A large proportion of these ventures seem to have come through the Kennedy Center. This is the second such appearance here of Jean Center in "Inside Daisy Mayme." Howard did serviceable duty for some time after its first Broadway success in 1932. Its theme is that greed is bad, and its humor in such fixtures as the outspoken comic maid, the jealous spinster, the pretentious matron, and the dapper but devious -- and pointedly Jewish -- art dealer. There is nothing in all this worth saving, much less resurrecting at great effort and cost. Stapleton handles the role of the lovable innocent appealingly, much as she did on television in "All in the Family." Pat Hingle blusters about as the master of the house, and Olive Dunbar squeaks indignation as the matron. But the difference between now and the 1930s -- when there were also plays of quality produced -- is that we do have television now, for those who want to see uncomplicated characters in simple situation comedies. There seems little need for people to take the trouble to see -- or put on -- such things live on the stage. THE LATE CHRISTOPHER BEAN -- At the Eisenhower Theater through February 27.