In most high priced markets, the listing agent is there for showings of multi million dollar properties. This is a plus and a minus for buyers and here are several scenarios.
1. If the buyers agent has not previewed the home.
This mostly goes pretty smoothly because the listing agent usually knows more about the property than the buyers agent. Both the buyers and their agent can ask all kinds of questions and get instant answers, everything from where are the property lines, the renovation background, and mundane things like how much is the average electrical bill.
The buyers agent does need to warn the client beforehand that they can inadvertantly tell the listing agent information that might not benefit any negotiation if they are interested enough to make an offer.
2. If the buyers agent does know the home.
Then the buyers agent should very politely ask the listing agent to give them privacy while looking at the home. In most cases, that would not be a problem unless the seller wants the listing agent along every step of the way, or the listing agent takes it upon him/herself to be "aggressive" and interject himself no matter what.
Listing agents will even throw out tempting lines that the buyer or the buyer's agent might want to pursue, such as the "motivation" of the seller to sell, have there been any offers, and anything else they can glean that might help in a negotiation.
3. If the buyers initiate conversation with the listing agent.
In some instances, the buyers just can't help themselves and will get into a conversation with the listing agent. A savvy listing agent will take full advantage of the opportunity to grill the hapless buyer and even get them on the defensive. Defensive meaning "trashing" other properties or locations which might include some that the buyer might have been considering. Buyers need to remember that there are pluses and minuses for each location and property.
What do I tell my clients before a viewing?
"Remember, the listing agent is there to SELL HIS LISTING."
"You, on the other hand, want to find one MOST SUITED TO YOUR DESIRES."