Although not quite the same, this reminds me of a very simple trick many blind people are taught during training on how to navigate the city: Never ever ask "Is this line 4" if you want to know which tram just arrived. Ask "which line is this?" Simply because the first version will make many people answer "yeah yeah" without even looking. The second version forces them to actually answer your question with something…
Oh wow sounds terrible to lie to a blind person but makes totally sense.
A lot of people are also too afraid to say they don't understand or hear you, and will just go "yeah yeah". It's aggravating, but it's both real and no real ill intent behind it.