What's spammy about it?

Check out the links in the References and (the second link) in the External Links section. Do those really add to the article or are they content-free "comparison" sites? The fact that you don't think the page looks spammy shows how subtle this game has got.

Edit: stable link to the page I was discussing since hopefully someone will remove the spam links soon: https://en.wikipedia.org/w/index.php?title=Lawn_sweeper&oldi...

Edit#2: Since I used to work in "whitehat SEO" (thankfully no more) let me explain what's going on here:

A long-lasting link from a Wikipedia page is like gold to search engines. It's far more valuable than if you linkspam a comment on someone's blog. It indicates that this page is very relevant to the topic. So when people search for "lawn sweepers", those links appear nearer to the top. The spammers monetize this by filling these essentially content-free pages with affiliate links to Amazon and other sellers.

There's no motive here apart from money. This doesn't make Wikipedia, Google, the web or even lawn sweeper sellers any better. It just benefits the spammers.

This is particularly prevalent in geographical articles. I recently spent a few hours clearing spammy links out of articles on Greek islands (and towns, and beaches, ...).

One strategy spammers are using to try to make their links in Wikipedia "stickier" is to insert them as citations instead External Links. Wikipedians will (rightly) think more carefully before removing references than external links, since refs are supposed to be providing justification for part of the article, not just a nice-to-have extra. But in most cases they are not really legitimate citations, in the sense of any kind of reliable source for information (either the information isn't even there, or it's copied from a better source like an official website, in which case the original source should be cited instead).

Maybe the 'brands' section that was just removed: https://en.wikipedia.org/w/index.php?title=Lawn_sweeper&diff...

Although it mentioned several brands so it seems a bit of a weak case for being a spam article.

This illustrates precisely why wikipedia is actually fairly robust.

Because anyone can edit an article, generally, there's a catch-22 for things like spam entries. If nobody sees it then it can stay around for a while, but then again nobody is looking at it. But if a lot of people see it then the problems tend to be addressed either because mods take notice or because individuals edit out the spamminess.

The problem is, search engines are looking at this content, and they are pushing spam links up their listings as a result.