I have a very low quality local pet store that has about 35 tanks. They actually stock some rarer things for such a small store (black belts, eels, etc.). Anyways, they hire just about anyone that applies there I think. I've bought GTs and let them think they were "Jack Dempseys" before (JD price of $5 GT price of $15). The fish aren't treated very well so I don't feel bad taking advantage of the store. Today I went down there to see what they had and I saw they had a tank full of rainbowfish. Anyone that knows rainbows will tell you that they can be rather expensive, except for the Australian Rainbows which are very cheap (around $2-3 usually). In the tank they had the labels "Turquoise", "Bosemani", and "Australian", but when I looked in I saw Boesemani, Turquoise and Iranian Reds. I assumed that they thought the Iranian Reds were the "Australian Rainbowfish" so I bought all of them for $6 each. Usually they retail around here for no less than $13 lol. I love that store sometimes 
Has anyone else done this?
Has anyone else done this?