GIVEN THE GENERALLY below-curb level of campaigning that Virginians are being treated to in this year's three main scraps for statewide office, it's not easy to separate serious allegations from soft-core innuendo. But even if the political air is filled with more charges than a testing room at a Delco battery plant, conflicts of interest deserve public attention; and Nathan H. Miller, Republican candidate for lieutenant governor, is the subject of two such reports involving legal and legislative connections that do raise questions.

First, there was the report that Mr. Miller's law firm accepted at least $250,000 in legal fees from the state's electrical cooperatives while he was drafting and voting for legislation that gave the co-ops $13.2 million in tax breaks and business advantages. At that time, Mr. Miller defended his actions by saying that he wears "two hats" in the legislature--one as a senator and one as a private lawyer.

But which hat--or was it another chapeau entirely? --was Mr. Miller wearing when, according to another report this week, he introduced and helped secure passage of a state law designed to help one of his law firm's longstanding clients win potentially lucrative mineral rights? And how about when a state judge ruled this law unconstitutional and threw out a suit brought by two of Mr. Miller's law partners, prompting Mr. Miller to get a fellow lawmaker to offer legislation allowing that suit to be resurrected? Mr. Miller was among those voting for both bills.

One can argue--and Mr. Miller is one who is-- that if Virginians are content with a part-time legislature, there is "going to be the necessity of their citizen legislators to make a living." It is true, too, that Virginia law does not expressly prohibit lawyer-legislators from voting on bills that may affect them or their clients. But the rules of the state senate do bar members from voting on matters in which they have an "immediate, private or personal interest."

This is the basis on which the state senate's leaders have called an extraordinary session of the senate's rules committee for today--as a first step in determining whether Sen. Miller should be disciplined.

Without prejudging the outcome of this exercise, a prompt committee review does seem in order. Charles Robb, Democratic candidate for governor, says he thinks that the investigation should be postponed as--and watch this shower of crocodile tears--a matter of fairness to Sen. Miller. But it is hardly fair to let all of this drift through the air unchecked; Mr. Miller deserves a swift and fair hearing. And he is familiar with this kind of campaign action, since he won his state senate seat a few years ago after accusing his opponent of conflict of interest.

In the meantime, voters may well consider whether it is necessary to await a decision by the state senate. It may be that their own political question can be answered without a legal finding--simply by deciding for themselves whether they approve or disapprove of the way Mr. Miller wore his hats and how he might wear a bigger one.