Pretty shixxy behaviour, these girls don't make much as it is. Have seen a couple of instances of Russians being cheap... one was outside a GGB where a lad had been inside throwing his tickets under the table.(Security were being bit rough with him). Another was a couple in a GGB who saw a sign for beer at 60 baht, then pointed towards my Heiny bottle and ordered 2.... when they got the tab the arguments started. Sadly I got the impression the server lost out.
The OP sounds blatant though, eat and dash in true Manchester, UK, style!