Generally speaking, these 'survey' sites are after a) your email address, b) any other personal identifying information they can weasel out of you, and (particularly) c) your cell phone number. Screens that request your cell phone number also reveal (in mouse print) that by supplying it you agree to receive text messages from some service for additional fees. What people find out is that these 'services' ding your cell phone bill for $20 or more each month.