Not as dirty as you think
I actually don't know this older female, but I think her name is Maggie. She appears to be around 5 years old and to have recently had a litter of pups. Anyone who has endured a sweltering Bangkok afternoon can attest to the importance of taking advantage of thirst-quenching opportunities, so when a dog comes across a couple of unsupervised bags of ice on a city sidewalk, she'd be foolish not to dive right in - and Maggie is doing just that! (However, it should be noted that more than a few unlucky hounds have been caught in the act, which usually results in a swift kick to the dog's posterior from an angry vendor).
Of course, for humans, this photo raises some disturbing hygiene-related questions -- particularly if you enjoy a nice Thai iced tea or coffee purchased from one of the thousands of streetside beverage vendors around the city. There have been rumors over the years that some vendors are so lackadaisical about storing their ice that they end up selling drinks with high levels of canine saliva. But the fearmongers who spread rumors and perpetuate sterotypes about dogs being dirty are ignoring scientific evidence that shows dog saliva actually kills E. coli and other harmful bacteria!
I'm not saying that people should go out and share their drinks and ice cream cones with the nearest Bangkok street dog they see, just that appearances can be deceiving sometimes.