Regarding this point, I've had this suspicion of so many subscriptions – to the point where I was questioning my own memory/sanity on the regular. I finally set up a label in my Gmail inbox called "Already Unsubscribed!". Every time I unsubscribe to a newsletter, I add a Gmail filter that marks anything from that sender with the "Already Unsubscribed" label. This way I know if I'm just misremembering unsubscribing, or if I'm actually being spammed.
Incidentally, I just checked that label after about a year of doing this. As it turns out, there's only one company that's ever continued to email me after my unsubscribe request. So I guess my memory (or sanity) has been failing me all this time.
(And no, the company is not Wikimedia) :P