There have been a variety of casts in the Rochester area, only one of which seem to be still performing these days.
An international directory of casts lists The Ancient Spirits of Evil as performing at SUNY Brockport as recently as September 2005. While the troupe has changed its name several times it has essentially been the same cast since the early days at Stoneridge Theater. They are now performing regularly (but not weekly) at RIT. Several cast members are hold overs and have been with the cast at the many locations where they have performed.
The Cosmic Vibrators, which later became the Mental Mindfucks (or Mental Mindf*cks) performed at the (also defunct?) Marketplace Cinema around 2000. They may have merged into A Rather Tasteless Joke — the web detritus makes it hard to tell.
A Rather Tasteless Joke
had shows in Webster, regular shows at the German House until mid-2004, and made a comeback at RIT in 2006. Many, many sites point to the cast's page as being [rochesterrocky.com] but that has been down since mid-2004.
2009/2010: It's now run by a group at RIT: Facebook Rochester Rocky Horror Page