For the record, I don't think this is that bad of a thing. If all of this is actually true (I'm not 100% sure it is), then it's certainly not on the level "actual spammers" perform at. Spam is basically unwanted and harmful advertising, and nobody complains when someone gets e-mailed an actual useful relevant thing out of nowhere. If the thing you're being e-mailed is more relevant than the ads GMail is showing you then I'm not sure you have a right to complain too much. Sure it may feel slightly off, but calling them "completely unethical" is going slightly too far.