I noticed quite a number of posts where someone would advertise an alternative serialization library, since I more or less follow the boost-serialization tag.
Just now, I got another one: Packing struct in Boost Asio buffer, and decided to have a look.
To my surpise, this user https://stackoverflow.com/users/1639596/wood-brian has almost exclusively self-promoting answers.
- The vast majority of his 39 answers mention and link to his library.
- Most often, it starts out with a link, and
- Not infrequently the answer has a tenuous link to the question, and sometimes, the answer doesn't contain anything more than just the link
I do realize this is at least in part a work of love. I do personally feel it's a bit too much, though, and it might have crossed the invisible line where it becomes abuse of StackOverflow for advertising purposes.
- In particular, I feel that all three "checks" offered in Andrew Barber's answer "Is it allowed to put links to personal technical blogs having advertising in SO answers or comment?" have been neglected
- The statistics in this much heavily-debated case were far less outrageous (Brian has a 90% advertising pay load rate, way higher than this "spammer"'s mere 16%!)
- There's jurisprudence in the Ira Baxter case (episodes 1..n, see "Limits for self-promotion in answers")
I don't know whether the guy has any commercial interest in spreading his library, but aside from that, the principle should be considered: when is spam spam, and when is it somehow acceptable? Or, when do we allow advertising, even though we prohibit it in general?
 In fact, it's easier to link the few answers that are not advertising his product:
- Best container for C++ class objects
- C++: fastest to write vector file to output in normal text mode (not binary) in C or C++
- IPC message queues how to send a vector of pairs
- https://stackoverflow.com/questions/13445172/how-to-boostserialize-an-exception/13445874#13445874 (on the bright side, he's maintaining his answers). NOTE This one links to his site, but doesn't directly advertise his product as the solution, so I don't count it in my list of "offenses"(?)
Update November 10th 2014 added a chapter to this story. In a now-deleted meta.SO question (https://meta.stackoverflow.com/questions/276430/a-stubborn-self-promotor-has-returned ) I exposed a list of newly added answers by the same poster. In the interest of historical reference, here is a screenshot of that question after @animuson handled it: https://i.stack.imgur.com/mB9y1.png