I'm happy to say that I would be fired if I did this, thought this, or wrote this comment.
EDIT: Parent used to say "it's common for salespeople to log in to customer environments to show potential customers what the product looks like with actual data in it."
I removed the part where I said 'it's typical for sales people to access customer environments', because I don't know how accurate that is, but probably happens more than anyone knows. Obviously it shouldn't happen without customers consent.
Also, reviewing the article again, the access patterns don't seem to match with this behavior, so there seems to be something else going on.
I've worked in enterprise IT departments for nearly 20 years and not once during a demo for any product has a sales engineer logged into a live customer or showed actual customer data