Yeah I've definitely felt this.
I once walked into a watch shop in a mall trying to see if they can help me adjust the hour hand alignment on my Orient Mako 1. When I approached the rep, I immediately sensed her judging me, as if she was purposely flashing her Rolex Ladies Datejust at me. She even had the audacity to say to me "you should get a better watch". I will never forget that.
It's unfortunate that people judge how much you're willing spend by what you've already spent /wearing, and I think in a way, that's just how luxury retail is for the longest time. From a sales-rep's POV, if they see someone wearing a $5k watch vs someone wearing a $150 watch, they can't help but judge because to them, that may be the difference between a sale and a waste of time. That said, I don't think giving a potential buyer attitude or passing judgement is okay at all; it contributes to this "snobbery" that we're all so sick of.
Don't get me wrong, I've also had great experiences with reps who are genuine watch nerds willing to just talk shop with you, let you try on multiple pieces, and without ever making you feel intimidated. That's the real way to sell. Sell the long term experience. Make me think of you when I want to buy that grail watch.