Former Detective Constable Nicholas Taylor, based at Bloxwich, advertised his enterprise online, but the operation was deemed to be off-duty conduct that brought discredit on the police service.
His activities came to light after a national newspaper contacted the force in November 2020, alleging he was offering threesomes at an hourly rate of £150 via an adult website. This prompted a professional standards investigation resulting in the officer being removed from any duties involving the public.
At a hearing on Wednesday an independent chairman found that the officer, who lives near Telford, had breached professional standards relating to his duties, responsibilities and instructions, as well as conducting himself in a discreditable way.
The hearing also found his behaviour amounted to gross misconduct and that he would have been dismissed had he not resigned.
Speaking on behalf of West Midlands Police on Wednesday, the force's barrister John Goss said the matter had not been investigated as "keeping or assisting in the management of a brothel" as it would not have been proportionate.
Alleging Mr Taylor had brought the police service into disrepute and misconducted himself by failing to declare a business interest, Mr Goss told the hearing in Birmingham: "This came to light as a result of an undercover investigation by the press.
"The facts in terms of what actually was being done are not disputed."
The former officer, who is believed to be aged in his early 40s, did not attend the disciplinary hearing but submitted a document describing the allegations as "part of his private life".
He also claimed what he had done was not a business interest and that readers' comments left below The Sun's article had been largely supportive, with only a small percentage being negative.
The ex-detective also argued his activities were "an expression of his sexual identity" and that standards change over time - with what was unacceptable in the 1970s or 1980s now acceptable.
He further submitted the force had taken an over-cautious and "prudish" approach to his behaviour.
However Mr Goss told the hearing that the fact Taylor and his partner had received payment, it was "quite obviously a business interest"
But Mr Goss told the hearing: ""Even if it is right that Dc Taylor simply never thought about it that way, he ought to have," he told the hearing.
"If he had turned his mind to it for a moment, as he should have done, it would have been blindingly obvious that it was going to be an issue.
"In this case the behaviour involved advertising to the general public with pictures of himself that were traceable to who he was. It involved inviting people to his home address who he did not know.
"We say it goes without saying that accepting pay from members of the public in exchange for sexual services is conduct which is capable of bringing the police into disrepute."
The hearing was told Taylor, who had 19 years of police service, was "already in the last chance saloon" because he had previously received a final written warning for neglect of duties, relating to a witness intimidation case in which statements were shredded rather than uploaded to a police system.
Mr Taylor subsequently resigned, but the misconduct process continued.
Concluding that he was guilty of gross misconduct, panel chairman Harry Ireland said Mr Taylor's activities were a business and "fell into the West Midlands Police business interest policy".
"Dc Taylor should have sought permission from the force to undertake his activities," he said.
Mr Ireland said the misconduct was a deliberate act and not a simple oversight and that it was "akin to a criminal offence" and "acting as a prostitute".
The panel chairman added: "This is not, as Dc Taylor claims, a moral judgment on his sexual preferences.
"We find the conduct was a breach of the standards of professional behaviour.
"As far as we could see there was a criminal offence involved, albeit that the appropriate authority chose not to pursue such."
Detective Chief Superintendent Sam Ridding, the head of West Midlands Police's Professional Standards Department, said: “We expect the highest standards of behaviour from our officers, both on and off duty.
“Like all officers Dc Taylor should not have engaged in activity that was likely to bring discredit on the police service, and any business interests should have been declared to be assessed for any potential conflicts of interest with his role within the police.
"He failed to do that, and his off duty actions brought discredit upon West Midlands Police.”
Mr will now be placed on the barred list, preventing him from working in policing anywhere in future.