I basically agree with you, but we have to realize that there are always going to be people that think certain aikido is fantastic and certain other aikido is worse than worthless. It's a legitimate opinion that a person might express without necessarily trying to "advertise" something.
Whether a person perceives an opinion as advertising or reacts to it as such is not under the control of the original opinion-expresser. If it really is opinion and one disagrees, express disagreement (or not) and move on.
Of course, it is also possible that the opinion is being expressed for the purposes of promotion, in which case it is up to the receiver to accept or reject the message (agree or disagree). If it really is advertising, decide whether you want what is advertised and move on.
We don't argue with the television when it tells us that a brand of noodles other than our favorite is "the best", but I do think that what you call "pressure selling" is counter-productive and annoying. It turns me off and seems kind of cheesy (unless it's for noodles, in which case cheesy is a good thing).
Yes indeed but having an opinion that 'a' is useless may well be normal but saying it does not make it legitimate or reasonable does it? That particular example is neither 'advertising' nor 'selling as better or supreme' but it is blatantly rude and offensive wouldn't you say?
In my opinion it cannot actually be true either for what anyone says is useless is obviously useful to those who do it. When I call someones art useless I may not be 'selling' but what am I doing?
Looking at what we say and knowing when it's negative is the starting point.
By the way cheesy is what I would call that guy doing the gangnam style rapping and dancing.