Though the long-awaited verdict this week on the Keating Five by the Senate Ethics Committee amounts mostly to a disappointingly mild scolding, it is still not without some sting.

In essence, the committee concluded that Sen. Alan Cranston may have committed major ethics violations but that no action is needed against the other four lawmakers. Even so, Sens. John Glenn, Dennis DeConcini, Donald W. Riegle Jr. and John McCain were in effect convicted of bad judgment.The committee's report opens the door to possible censure of Cranston by the full Senate. For all five men, the 14-month investigation inflicted painful embarrassment and tough lessons about public probity that should be long remembered not only by the lawmakers but also by their constituents.

Specifically, the committee found that Riegle's and DeConcini's actions gave the appearance of being improper, while Glenn and McCain "exercised poor judgment" in their dealings with Charles H. Keating Jr. and his troubled Lincoln Savings & Loan.

With the aid of Keating's political clout, Lincoln Savings & Loan stayed open two years after regulators recommended its seizure. The government took over Lincoln in April 1989 and found it insolvent. The taxpayers must pay more than $2 billion to bail out depositors.

By detailing how the senators arranged meetings and lobbied for a man who gave $1.3 million to their campaigns and causes, the committee gave ammunition to opponents of all five lawmakers in any future bid for re-election. And the lawmakers will long bear the stigma of being known as the Keating Five, a derisive term that prompts nose-holding.

But the committee was kept from getting tougher because of the lack of hard guidelines about how far it's proper for a lawmaker to go in helping constituents.

That means the full Senate will still have some uncompleted business even after it finishes dealing with Sen. Cranston. Since the judgment and consciences of individual lawmakers evidently are not always clear enough guides in some cases, the Senate should help draw a more definite line on where constituent service stops being legitimate help and becomes a sell-out.