I'd say there are degrees....frankly the emails I get regarding a domain for sale are horribly written and often, difficult to read. But occasionally, I get a well written piece that is articulate, thought provoking and presents a compelling case. Being in the latter group, is not a bad place IMO, but I know it is all spam.
As I had posted in another thread, I am currently test driving Domainero, which is at it's core, a spam machine. Some of the recipients are probably other domainers, though I try to remove them. But, it is generating some discussions so for me it seems to be worth the risk of being called a spammer. But again, I do send a well crafted piece that tries to help them envision what they can gain from taking a look as an end user. As a business owner, If I can gleam even one idea from an unsolicited email, I'm OK with the rest of it. I am completely unconcerned with what other domainers think of the practice. They aren't my suppliers or my customers....they are my competitors.
BTW, comparing a sports care purchase to a domain purchase is an incredibly naive argument.