Any particular areas you had in mind?
This reminds me of a members post on the original and now defunct Korat Farang forum. Must be about 2005/6 that a member posted this exact query and the thing was, that at that time, there weren't many other farangs around in Korat, unlike now. So after he made a post about this, the next time I went to the Mall (the only store at that time), I made a point of acknowledging any other farang I saw and got blanked every time!
In my 18 months living in Korat, I got into conversation with just three other farangs, where we did meet by acknowledging each other, whilst out and about, as opposed to in a bar or something similar.
One was a Brit who used as I did, fitness first at The Mall, and we regularly chatted when we saw each other, but he worked off-shore so came and went. There were others there but they studiously ignored everyone else, which was the starting point of our conversation.
The 2nd was a Canadian, who like me, was holding the trolley whilst the other half whizzed around Makro. He was not settled in Korat, but was rather, seeing if it would suit, and he asked me lots of 'where is' and 'how' questions.
The 3rd was a German Aussie who I bumped into in Tesco in Hua Talay, where I stayed in Korat. I didn't see him approaching me, but he actually came up and said hello and that he hadn't seen me before! We chatted for some time and he was a really interesting guy, German born, but hated Germany and emigrated to Australia, which he loved and it was really the cost of living there, that had seen him move to Thailand with his Thai wife on a permanent basis.
But generally, I find that there are so many farangs in the area and many of the main centres in Thailand, that there is no surprise in seeing them anywhere now and I doubt many of us acknowledge others in our home Countries.