I'd certainly like to think I'm an ethical developer, and I always implement the delete as a flag.
I, however, do not implement an easy way to retrieve deleted data without going into the database or through an administrative interface with heavy auditing.
It isn't just about data mining for customer data -- it's about data mining for site usage and user activity. Using metrics off of visited web pages or tracking that way can be too convoluted when the KISS method is: flag it on the data side and you can interpret flow.
I, however, do not implement an easy way to retrieve deleted data without going into the database or through an administrative interface with heavy auditing.
It isn't just about data mining for customer data -- it's about data mining for site usage and user activity. Using metrics off of visited web pages or tracking that way can be too convoluted when the KISS method is: flag it on the data side and you can interpret flow.