Germany has a relaxed attitude to prostitution and other types of adult entertainment. Prostitution is legal and the girls run it as a business and pay their taxes to the German government.
Eros centres are a place where normally a girl rents a room, and manages her clients herself. Normally these are very safe to use.
FKK clubs or sauna clubs normally are well maintained, some with swimming pools and saunas. Some clubs have a day price and you can negotiate with the girls for extra services.
Table dance clubs are just a good night out and very popular, some have attached an Eros centre.