It has been such a success that the dolls are booked around 12 times a day, costing €80 ($131) per hour.
Schwarz said: "For many it is not a fetish, but more of a curiosity."
She added: "Actually I was looking for colleagues with good knowledge of German for the S&M scene, because for these practices communication is very important. But I did not find any."
The brothel operator said that men of every age and profession from all across Germany have flocked to her brothel.
Schwarz said: "From those on benefits to judges. Seventy per cent of men also come back."
Bizarrely, Schwarz said that the wives of many brothel visitors are reacting "with tolerance" to their desires and are often seen "waiting outside in the car" while their husband is having sex with a doll.
She said: "They see it as a toy."
Schwarz has only had one bad experience at her brothel so far, when an overly excited customer broke a doll, "Anna" - the most popular one in the establishment.
Schwarz said she had to order a new one.
According to reports, sex industry experts estimate that people with a fetish for sex dolls are a growing group, and that they expect more dolls to be made available by brothels.
Austrian psychologist Gerti Senger explained why some men are more interested in sleeping with sex dolls instead of a real woman.
Senger said: "First, the man can do anything with the doll. Second, every intention is turned off, which can be a factor with a prostitute."
But Senger, who is a co-chair at the Austrian Society for Sexual Research, said that she was shocked by some dolls being more popular than real prostitutes and called it "a real autistic tendency".
It was reported earlier this year that sex doll "Fanny" became the top-selling superstar of the "Kontakthof" brothel in the Austrian capital of Vienna, getting more customers than the real prostitutes.
At the Ars Electronica Festival in the city of Linz, an interactive silicone sex doll named "Samantha" became so popular that it broke down because so many visitors groped its breasts and soiled its body.
In Germany, a new brothel has now opened that caters exclusively to those who are attracted to plastic sex dolls.