You can't trust advertising completely nor can you trust reviews completely but they are signals. Treating things as binary will not get you anywhere. Signals exist and are useful if not 100% accurate.
This is... an understatement. I would agree advertising is a useful signal, but I would say that not only can you not trust advertising, you should put negative weight on advertising - i.e. whenever you see an ad, that means the company is putting some amount of money into trying to convince you by means other than an honest comparison/spec table, and therefore is likely to have an inferior product. So personally, I generally avoid any companies/people whose presentations contains no information about the objective characteristics of their work.
Id like to believe people have enough agency to do a google search to at least figure out their options, but granted, I might be wrong about that.
Edit: I do agree you should have a google-findable website which lists the objective characteristics of your product. If you call that advertising (I call it a "release", and I reserve the word "ad" for anything that has emotional appeal and caters to the indifferent/uninformed), then I agree.