How to make yourself look bad: broken bounce addresses
We get a certain amount of email with envelope sender addresses that look like your typical modern mailing list software's bounce management handling. They have what looks like individualized addresses and often have 'bounce' in either the local user part or the domain (such as an email message from 'bounce.global.expediamail.com').
I don't particularly look at sender addresses of email to our users. I know about these messages and addresses because some of our users autoreply to these messages, and those replies just sit there on our mail server until delivery attempts time out after a while.
(I do look at our mail queues from time to time, including at the destination addresses of email that seems to be stalled.)
You can guess how good this makes these places look, or more to the point not look. Sending out email that simply fakes all of the signs of a good, well-managed mailing list is an old spammer trick, and this is awfully close to it. At a minimum this shows a significant lack of care in the implementation of these places' mailing list management systems, which isn't likely to make people feel more comfortable with their other mailing list practices. (After all, if they're slipshod with one aspect they're probably slipshod with others, like who they add to their lists and how easy it is to actually unsubscribe.)
Of course I know that this is optimistic. At least some of these places are likely merely going through the motions on responsible mailing list management with no actual substance behind it; in fact, their business model or marketing approaches may actively prevent it. This is a great way to really irritate a certain amount of people but that doesn't seem to matter to these companies (either morally or practically).
(I don't know if this is an active decision to break or not implement accepting incoming bounce messages, or just an accident where the people responsible haven't particularly noticed. Of course there is zero point in spending time to try to tell places such as expedia.com or nvidia.com that some of their email system is broken. If they actually cared they would already know; why they don't care is at best of academic interest. There is little functional difference between incompetence and evil to people outside these companies.)