newbies to what? the internet in general?
I mean to a particular Web forum.
I feel like "thread exhumation" is fairly universal, with its protocols for how to do it politely varying little across the internet.
Yes, it is universal. Established users of a forum don't usually get in trouble for it because they don't do a lot of it on an ongoing basis. New users are more likely to come in with a head of enthusiasm that they have not been able to discharge through prior participation (typically as a result of lurking without having had an account), and to irritate established posters by adding to many old threads in rapid succession, when it would probably work much better to spread out the exhumations a little in time.
On this forum revival of old threads has become a source of heat in the past, which is why we now have a 120-day warning that displays when a user composes a new reply to a thread which has had no fresh replies for that interval. On another forum which I used to moderate, we had a few members (some new, many of whom were young) who seemed bent on adding new posts to the oldest threads on the forum, which meant going back to many threads which had started in 2001 and petered out (for the most part) by 2002 and adding fresh posts with 2007 dates. This led to calls for the old threads to be locked to prevent this form of exhumation.
I was actually viewing "Who's Online", saw a guest reading this topic, and posted in it.
You mean this listing?
https://www.aaroads.com/forum/index.php?action=whoThat isn't really a good way to choose threads to post in. It is generated in arrears (i.e., the database doesn't have a notation that user X is viewing thread Y until
after user X has already loaded at least one page for thread Y), so there is no guarantee that a new post to that thread will be seen by that user. There is, however, a guarantee that many users will spot the new post in that thread in the "Most recent posts" listing, and wonder why it has been exhumed, especially if the new post feels to them like a placeholder.
It is much better to choose threads based on your ability to post something substantive and well-thought-out. This is more likely to attract a positive response: as economists say, a good signal is both difficult to make and difficult to fake.