Do not send unfundable companies Paul Singh’s way. He might stop taking your calls.

“You send me three bad deals, and we excommunicate you,” the 500 Startups partner said this week in a blunt assessment of bad referrals.

Singh, who acts as the seed fund’s de facto East Coast representative, tracks just about every bit of data available. That includes the track record of the people who introduce entrepreneurs to the Silicon Valley-based firm.