crossing the private/ privacy/ invasion/ creepy line may not be to do with law but more to do with culture

It is probably easier to cross the creepy test than most people think, and the issue being damage to brand and not achieving any value. An example could be using Bluetooth to track shoppers, whilst anonymous the direct marketing targeted to your on your handset feels like an invasion/ violation.  There is probably another axis which covers off adoption/ acceptance/ knowledge.