“Dark pools” -- private exchanges based on private negotiations between agencies and big media companies -- potentially do a great disservice to advertisers, according to Vik Kathuria, Global Chief Media Officer at Razorfish. Lured by the promise of brand safety, there’s a real “probability [brands are] being overcharged,” Kathuria told attendees of OMMA’s RTB conference, on Thursday. Though the risks associated with dark pools are well documented, many advertisers remain in the, er, dark on the subject. For many agencies, it's a question of "whether you're willing to educate the client," Kathuria said. Bigger picture, Kathuria said the real issue is hitting your clients' desired key performance indicators. Whether the exchanges being used are private or not, he said, it “shouldn’t really matter if you’re hitting your clients’ KPIs."