Went to my local outdoor market and a lady there was selling quite high end makeup (e.g. dior mascara, bobbi brown and MAC makeup).
I purchased some MAC pigment at £4 - bargain price I thought (rrp £14) but later found out it was FAKE!
There's a good video on youtube explaining how to discover fake MAC products - tip is, if the makeup does not have the 'name' of the colour (e.g. girlie pink) then its not real.
I was GUTTED! Just goes to show - if it seems too good to be true, probably is :(