The prospective buyer starts in a friendly manner, trust is built up and then: yes, but... can I bring an appraiser with me? This is an age-old trick, but it is being used more and more often. What the appraiser will find out is clear, defects here, defects there, best is to tear down the whole house.
In fact, it's the market, demand, price, not the valuer that determines the price.
But the prospective buyer tries to give exactly this impression.
Don't be taken for a fool!
Shortly to the real estate agents. There are good and bad ones ! Most of the time...