@Stuart *********
we're not talking about sending money. The op was asking about withdrawing money from the atm and using that banks atm conversion. For US dollars the conversion the atm gives me is always at least 2-3 baht per dollar less than what my home bank gives. When you add in the 220 baht fee it ends up being close to a 10% loss.
Perhaps I shouldn't use absolutes, since one may have a crappy bank at home that gives a terrible conversion, but I think that's rare and most people would agree to never accept the conversion at the atm.