Once they see this they'll go through all the mysql (or whatever database they are using) transaction logs and see anyone doing this and will reverse all the profits. So anyone doing it is going to get their mula taken away.
So don't even try to get away with it..
You may be seeing it with Tobacco others see it in other products
Just hope they let me kep the couple extra hundred K I made for going through the hassle of reporting it.