I've never blocked anyone, and I doubt I ever will. There are a very, very few who toss up posts that I may just skim over, since they could have a constructive one here or there. In these isolated cases, I subscribe to the "broken clock is right twice a day" theory, I guess. I've had a few folks chap my heinie a time or two...or three...but I'm just not much of a grudge-holder, even IRL. So, I get over the occasional slights almost instantaneously...most of the time. I'll admit to snapping a time or two, but I didn't even block those guys...or even remember who the other Bear was in the case where my inappropriate retort was rightly deleted by the Mods!
As to unsubscribing, I do the same...when it's becomes boring, irrelevant to my interests, excessively repetitive, etc.
Blocking individuals that are detracting from your enjoyment of the board and unsubscribing to threads that do the same does seem to be the answer, though. Aside from some obvious "Cesspool" threads (Thanks Markojp), it's the otherwise legit, positive, and constructive threads where the Mods may need to occasionally step in to ward off clear trolling behavior that has barged in unwanted.