I did ignore the obvious benefits of both the Tory and Labour NHS 60th birthday cards as I didn't think data harvesting was very interesting or new. But PragueTory alerts us all to a less than ethical application by Labour on The Stirrer, and this links to general trends of reluctance to give data. The Labour card ask for names and emails but once signed you are on the list until you write personally to Gisela Stuart to request removal; I am not certain this is legal never mind moral as marketers are required to offer an opt-out clause to avoid future communication and cross-selling - in other words opting out should be the easy option not made difficult.
But there is a broader point. A colleague presented to the group a week or so ago and argued there was substantial anecdotal evidence within the marketing industry that suggests people are more likely to opt out than in, perhaps no great surprise. But parties if anyone need to be able to contact people as easily and cheaply as possible; hence they need to get people to opt-in. In other words, rather than making it hard and unattractive, the contact needs to be made wanted. Initiatives such as the Big Conversation maybe had that selling point for a short period, but blunt and obviously ill-considered data harvesting just turns people off.