I think what it all comes down to is, what is the intent? The line from okay to icky is probably a fine one in most cases, might depend on the situation, and in the end comes down to personal opinion.
How does one determine intent when looking at a pen name?
Usually, this conversation crops up after someone has been outed.
Yet I have seen how this whole debacle (not on kboards but out there in socialmedialandia) has managed to point accusatory fingers at people who simply use pen names for business or personal protection, accused of being dishonest and disingenuous and gross for having a pen name at all.
They try to choose names that point to obvious choices of pen names, and they're smeared.
They try to choose normal sounding names, and they're smeared.
Their business practices are called into question and they're accused of acting with ill-intent. They are immediately conflated with people who did use pen names for bad intent as if they all are doing it.
Do pen names need to carry a disclaimer?
"This is a pen name and is not intended to present as a real life person. This pen name was chosen specifically to appeal to the current segment of genre readers the writer wishes to write in. Any resemblance to actual persons, living or dead, or actual events is purely coincidental."
If you're not bothered by lying and using a persona to get intimate details of stranger's personal life, and are prepared to take the heat when you're discovered, then continue on. If not, might be time to rethink the whole thing. That's pretty much the same with almost any situation. If it works for you, great, but if not, regroup.
Sadly, this sort of behavior is not solely in the purview of writers. It's also the risk we all take when interacting online. As people who engage in online social activity, seems to me we hold some self-accountability to be careful who we give our personal information to begin with.
What gets me is that when I first started on the internet, this was par for the course. Don't give people your real name or identifying information.
On the internet, nobody knows you're a dog.