For some consumers, social networking sites have taken on personality traits that reflect who they may log in as and communicate with. Facebook might be a boyfriend. LinkedIn is a boss. Twitter is filled with acquaintances to say "hi" to in the hall.
The lead shouldn't represent the beginning of the sales cycle. Sales cycles should start with thought leadership that informs prospects about future trends that will result in business challenges and opportunities—enough so the prospects have an "epiphany" about their needs and enter the sales cycle.