Herbert and Mary Cole, former landlords of massage parlors, topless bars, and peep shows on 14th Street NW, have lost a bid to set aside the guilty pleas to tax evasion charges that sent them to prison last winter.

The Coles claimed that defense attorney Kenneth M. Robinson did not properly represent them because at the time he was negotiating their plea-bargain Robinson himself was the target of a federal tax investigation.

However, after listening to three days of testimony and reading a thick pile of depositions, U.S. District Judge Thomas A. Flannery rejected the argument. He said both Coles will have to serve out their sentences.

"The evidence shows . . . that the Coles' acceptance of the plea bargain was a carefully calculated business decision," Flannery wrote in an opinion released on Thursday. "The Coles knew their former business associates were cooperating with the government and testifying before the grand jury. Herbert Cole desired to avoid the trauma and expense of a long trial and the risk of forfeiting all his property. . . . "

In addition to his plea on income tax evasion, Herbert Cole pleaded guilty to racketeering charges stemming from his involvement in two massage parlors that prosecutors said were fronts for prostitution. He agreed to forfeit $1.5 million -- for back taxes and fines -- from the sale of the Casino Royal building, at 14th and H streets NW, on which he made a profit of almost $4 million.

Prosecutors agreed not to oppose a request by defense attorneys that the Coles be sentenced to no more than six months in prison apiece.

Flannery said the plea agreement obtained by Robinson "can only be characterized as remarkably favorable to the Coles . The only 'adverse effect' from Robinson's representation was his tactical decision to seek sentencing by a judge Flannery himself who turned out to be unwilling to go along with the six-month sentences . . . . "

Flannery sentenced Herbert Cole to two to eight years in prison, which under parole guidelines will probably keep him incarcerated for at least six years. He sentenced Mary Cole to six months to three years in prison. She is expected to serve at least two years.

Mark Foster, one of the Coles' current attorneys, said they are considering an appeal.