First note - It's a hypothetic situation. Say, you have the following general info: Customer name, purchased product, email, phone, address. What would you do with it? Fred
There are a lot of things you could do. Various types of marketing as well as other methods such as destroying your competitor's reputation or even reselling the database to x number of other firms.
i guess that would depend on what kind of person you are. some would spam hell outa them, some wouldn't. some would try and sell the list. but i think most would just sit on it as that would be the reputable thing to do.
And someone also says that business has nothing to do with ethics... But in any case, one can't keep in secret that they use such DB for their own purpose. Btw, selling the DB can bring the seller direct to the jail, unless the buyer is very very reliable.
Chances are I would never get it to begin with. However, I would not use it because I try to do things as upfront and honest as possible. I found that what you do comes back at some point. I may make less than some but at least everyone who deals with me know that I will be upfront and honest with them.