Are the coins really checked / refused? I mean, I realise why that would happen (to prevent someone simply dumping their fake coins straight into their account), but I never thought the coins go through more than a sorting machine. Maybe there are more checks for businesses taking payments almost entirely in coins...

This provides some interesting incentives though... if you can sort the fake/real coins yourself in some way, you can deposit the real ones and use fake ones to pay all small bills (pay utilities, petrol, etc. with coins only)