1) Lot of noise in the internet. You are right. Coming from "innocent" people with a secret agenda, whether from the manufacturers' side, or themselves profit motif. The key is to get to know the people online or personally that you learn to trust, both integrity wise, and from the perspective of matching their taste with your own. This takes years (if not decades) and constant exposure to what goes on in the hobby, user forums and publications / reviewers.
You're right, when it comes to opinions in audio, it can take years to find people who you can trust.
The same thing applies to cars, electrics, plumbing, health etc.
I still have fond memories of Derek Whittington who ran Sound Advice from Loughborough. I bought my first system from him and I'll always be grateful for his honesty and patience.
He was big on Linn and Naim, like so many were back then, but neither Derek nor anyone in his shop ever pushed anything on me.
I remember one difficult listening session where I couldn't find a single well reviewed loudspeaker I liked more than what I had already until someone there suggested listening to the Rega Kytes.
That was a classic case of using your own ears to make a purchasing decision.
As you say, trying a product at home would be best but listening at a dealers is still far better than taking a gamble on what you've read or heard.
Howard Popeck is another name that comes to mind. Years ago my sister fancied some new speakers and auditioned some Harbeths at home. She was unimpressed until Howard suggested listening to some vintage JBL L100s which she still loves to this day.