our reporter oliver sallet went along with two of them. reporter: when night falls in athens, tina papoiti and nikos tsepenekos start their patrol through the amusement district of plaka. the two inspectors are on the lookout for tax dodgers. their suspicions are aroused in this cocktail bar. >> there are no bills on the tables. reporter: it looks as if the owner is selling his drinks off the books. >> good evening. we are tax fraud inspectors. could you please give me a bill for ten cents? reporter: each bill lists how many receipts were issued that day, an important clue for the inspectors. many guests don't ask for a bill. and with vat at 24%, the temptation is great to pocket the cash. >> no, that's not a bill. just an order. >> just 32 bills for the entire day? >> let's have a closer look around. reporter: this is the second time the owner of this bar has been caught out. his fine is doubled to 500 euros. he won't speak to us while the camera is running. outside some guests are sympathetic. >> if we had lower taxes or the money was us