What's so Warm about a Warm Market?

One thing that bothers me about network marketing / old school MLM is the idea of working your warm market. The warm market being your so-called circle of influence: those people who you run across each and every week and also those you haven't seen for a while. This would expand the warm market to the people you went to high school with but haven't spoken to since gradation day. A lot of network marketers have claimed they have moved past that.

Yet just the other day, I heard a well established network marketer telling her group to use the warm market approach. She cited a few stories of this type: Joe didn't talk to neighbor Mary because Joe didn't think Mary would be interested in a home based business. Mary then went on to sign up under someone else and went on to be a six figure earner - yada yada. Ok, in every warm market, there are potentially a few good prospects. Is it worth taking the enormous amount of time talking to all of them just to find one or two good prospects?

This marketer was saying this from the standpoint of not turning our backs on any market. While that is a point to be considered, wouldn't you rather invest your time in people who have at least expressed some interest in a home based business? It doesn't matter if you don't know those people (yet), it's easier to talk a stranger who has raised their hand and said "I'm interested in a home based business" than to talk to a friend who has not said anything about it all.

I think the "warm market" approach only works for a very select few (gregarious and extroverted) people who strike up conversations with everyone. What do you think?