Haha, I wonder if it's the same place I went to a year or so ago. It was a siu mei restaurant in Mong Kok.
They had lots of pictures of dishes on the wall but they were really expensive. The lady gave me an English menu but it also only had a few expensive options (as in the cheapest thing was $75). The table had a printed Chinese menu under the glass (not a set special), and that menu's cheapest item was something like $17 and the most expensive thing was $80, with most things running in the $40-60 range.
I asked the lady in Canto why the menus were different (my speaking was much better than my reading then), and she just asked me what I wanted to eat. :P I told her cha siu rice, which turned out to be $40 or so. It wasn't very good either, so sounds like it could be the same place!
I guess in that case they're not technically cheating by having different prices for different languages but they just don't bother to translate the cheaper, more normal options.