As a buyer, when you are walking through a home, keep in mind that the seller might be listening! 

These days, there are plenty of ways that a seller could be monitoring their home, with a security camera, or other recording device that could allow them to hear every word you are saying while you are in their house.

And, these cameras (or other listening devices) are less and less obvious and less and less expensive!

So.....

1.  Don't insult their house.  It won't help during negotiations.

2.  Don't discuss negotiations.  You might be revealing your strategy.

One way around this is to pretend (as a buyer) that the seller is walking through the house with you.

By the way, sellers, it may not be legal for you to record conversations in your home while you are gone.  You should likely either NOT record conversations, or disclose that it is taking place.
 
P.S.  I am not an attorney.  Consult one if you want an actual legal opinion.  Ask me if you need a recommendation.