There are people that make up a small segment of the population that have an unsatisfied need to see the insides of other people's houses. There's also a segment of the population that don't quite understand the "big picture" of how service professions work... for example, any group of friends going into a restaurant and requesting a table and sitting at it for over an hour, but feel they don't need to leave a tip because they only ordered espressos or shared a desert. Sure, you're paying for the service of a service professional, but it should also include their time and resources you consume outside of the actual service but many don't have that perspective. Why should I pay you if you aren't providing your actual "service" to me even though I'm consuming your time and resources that would be earning you your expected salary otherwise, is their justification. So when you encounter an individual from both small segments of the population mentioned above, the result is the problem your wife faces with perspective buyers.
I look at the Agent / Buyer relationship from a different perspective when I encounter these no-harm intended individuals. I don't see it as the buyer is hiring the agent... for if that was the case, a contract of some sorts would be involved detailing the menu of services provided by the agent with associated costs, the buyer would make selections from the menu, pay the costs, and services rendered. but that's not how it works. so its important to understand the perspective of the agent looking to hire the buyer.. you're not paying the buyer to be your client, but you are looking to select the prospective buyer that's going to generate cash flow. In a commissions based work force that is also your main source of income, you have to look at prospective clients as that.. simply prospects..but who are a vital component of your salary. So when allocating your time and resources, especially if you're dealing with several prospects, you literally have to turn away these cold leads who are just looking for design tips and paint color pattern suggestions and you as their escort. If I was in the shoe-making business, i wouldn't hire a walk-in, give him access to materials and work space with the assumption that if its to his liking, it'll generate profit towards my salary needs, if the only thing he's interested in doing is looking around at all the other shoes, a behavior that requires my presence, time, and resources. You almost can't even justify it as "looking at it as possible income in the future" if it's costing you revenue now, whether its in the form of having to neglect actual buyers or you could be investing your time in things that would impact salary needs, such as advance course work (attending optional trainings offered by your broker), or investing time finding more serious leads.