When the man entered the home of the suspected prostitute, police on a stake out snuck up and listened through the wall.
The officers were treated to a symphony of grunts and moans, after which they concluded that the couple were engaging in sex acts.
The 46-year-old was arrested and on Tuesday he was convicted and fined for violating Sweden's laws prohibiting the purchase of sexual services, TV4 news reported.
The incident took place in September of last year when the 46-year-old made the trip from Växjö to Karlskrona in southern Sweden after responding to an internet announcement placed by the woman advertising massage services.
"I was having problems getting an erection and wanted to see if getting a little massage would help," the man said during questioning, the local Blekinge Läns Tidning (BLT) reported.
He told the arresting officers, who had received a previous tip about the woman's prostitution services, that he and the woman had only engaged in oral sex.
The 46-year-old added that, even though her "treatment" failed to cure his alleged potency problem, he agreed to pay the woman 1,000 kronor ($160) for her efforts.