FOR THE BETTER part of two years and several levels of investigations, there have been reports, allegations, insinuations, predictions and political whispers of corruption in the administration of Montgomery County Executive Charles W. Gilchrist. It is loosely referred to as the county's "liquor controversy" or, in yet another witless adaptation/warp, "liquorgate." It is also--if the public finally has been treated to the last of the state, independent, county and journalistic investigations-- much ado about nothing. Above all, it is neither a useful nor fair issue for the county executive election campaign now under way.

That is not, repeat not, an endorsement of the incumbent. The campaign is young and the options best kept open until more is seen and heard from the field. But because insinuations, charges and suspicions of wrongdoing tend to linger long after the evidence shows nothing illegal, the record should be made clear.

It all began in the spring of 1980 and centered around allegations of conflict of interest and mismanagement in the county-run department of liquor control. In addition there were related issues, including a $2,000 loan to an aide of Mr. Gilchrist, and alleged favoritism in the selection of the department's deputy director. State, county and independent investigations turned up nothing illegal:

* Independent auditors hired by the county said they could not prove charges that the department practiced favoritism toward certain distillers.

* A seven-month grand jury investigation by the county state's attorney's office ended without bringing charges after looking into allegations of bribery, favoritism and questionable purchasing practices.

* A lawyer hired by the county council found nothing improper.

* An assistant state prosecutor looking into that loan found no law broken.

* A 14-month study by the county's Merit System Protection Board found some procedural violations in the hiring of the deputy director--interventions attributed not to Mr. Gilchrist but to aides, and long ago acknowledged by the county executive.

The county's tab for its investigations has been estimated at $370,000, which, given the results, might suggest to some taxpayers that it is time for everyone to change the subject, and would-be political opponents of Mr. Gilchrist might well take note