I don't think the guide has a quote about the merchant. But I think, the golfer has a quote similar to what you mention about the merchant - and since the merchant on the other hand do likes the golfer, you likely would see that quote, if you move the golfer near the merchant. so, they recognize each other, and, in that case, the merchant will be happy about that, but the golfer not as much.
I'm not sure about the guide + zoologist, I usually use merchant + golfer + nurse to get the forest pylon. (by the way, intesertingly, while something like merchant + golfer alone is too weak to get the forest pylon, when you have the 3 together, it makes the merchant happy enough to sell all pylons (based on where he is, even if it's not his favorite biome. desert might be an exception though, since he dislikes that biome.
As for the desert pylon though, nurse + arms dealer should be strong enough to make the arms dealer sell the desert pylon, when they're in a "pure" desert (not hallowed). so, I dunno what could be the problem there. maybe their flags are too far there?