I’m waiting in a dentist’s office and two other patients, who are both in the construction business, are talking about customers of theirs whom I happen to know, and the comments weren’t very positive. I’ve heard people on trains screaming into their cell phones about companies which are clients of mine or in which I own stock. I’ve heard attorneys talking too loud at dinner discussing their cases.
Watch your mouth. You never know who’s listening (or, these days, even recording). There is absolutely no reason to discuss confidential issues (or brag about your work) in a public venue where you can be easily heard. If you don’t observe these ethical guidelines, some day they’ll all be talking about you and your former career.