Folks, reality check time.....
1) Amp techs, and their ilk are not usually the fun loving party animal types...... in fact thay have a tendency to be anti-social.
2) Customers who think they have been done down have a tendency to roar and shout sometimes, calling names and once in a while needing the police called. (I worked in a shop back when dirt was clean, it ain't any better now, I'm betting). Mostly it's when they don't want to pay the bill, but it does vary.
3) After a few rude, loud, and demanding customers, anyone begins to get a bad attitude.......
4) Even for an anti-social tech, it's generally considered rude to diss on the customer's stuff, unless you do it politely for specific reasons... we had some brands and models we frankly told customers they should get rid of, AND the reasons for it.
5) A lot of techs are not such hot players (but some are really really good), so their opinions may be a little "disregardable", shall we say......... If you for some unknowable reason, are still playing a Marlboro amp (did they make any bass amps? I don't remember), and like it, that's your thing, and you don't have to listen to, accept, or "take" the abuse if you don't want to. Vote with your feet if you don't like it. Elsewise, let it roll off.....