You know in large crowds on sidewalks in major cities, generally, there's one side for each direction of pedestrian traffic. We stick to the right, like the roads. And within the single direction of traffic, not as cleanly, there may be a side that is also used by faster walkers, dodging in and out of slower clumps of pedestrians.
Not in Bangkok. There's no trend whatsoever. Even escalators are switched around. The up elevator sometimes is on the left, sometimes on the right. No wonder why the Thais are confused. It's so bad they had to mark the sidewalks.
The only strategy to being able to walk while minimising- but never ever eliminating- dodging around and avoid crashing into oncoming people no looking where they are walking is to never make eye contact. The minute you do, they assume that you are giving way. Especially if you're a farang.