Then there is the facebook like button - this is either to unlock something or because you have just watched a video ad. I never do this. If I click the like button, I don't even know who sees the like. People I know friends and relatives on facebook in particular and just anyone who knows me might see that I have liked something. It might look like a recommendation. I don't know anything about the seller and I want people I know to trust me. In addition, not all sellers can be trusted. So, I leave without clicking the like button - every time.
There is probably a way around this but I can't be bothered. If a potential seller wants me to buy something eventually, he or she should make it easy for me