Before I start - 'the Market' is the Android Market, the official-but-not-exclusive app store for Android. Unlike the Apple iPhone App Store, the best known the the current crop of app stores, the Android Market is pretty open - anyone can sign up, anyone (within geographic limitations) can sign up to sell apps, and once you're signed up, you can push a new or updated app in a dew seconds, with no approval or delay. That's a good thing in many ways - for example, I've pushed multiple bugfix releases of my main app in a single day when I had to - but it also means that there's a lack of control, not so much for quality as for outright abuse. Google do have the right, and ability, to block individual apps or developers from the market, and there are a few cases where I really think they should be a bit more active at preventing abuse.
There is one serial abuser who stands out above all the rest, and a couple of others who are obviously breaking the spirit, if not the letter of the Market terms and conditions. There are also a few borderline cases, where there is definitely some abuse going on, but not necessarily enough to be worth taking action on.
Khalid Sheikh aka Perfect Acumen, now running under the name Sapphire Apps is by far the worst offender. He was famously booted from the iTunes app store after their supposed approval process allowed him to publish 943 apps, about 1.25% of the total published apps. Presumably, he's had to change his name in the Market twice because his previous accounts have been closed, but given that it only costs $25 to open a Market account as a published, and the apparent lack of oversight which has allowed him to return, he'll just keep coming back.
He's a spammer because of the volume of apps, the fact that most of them are priced entirely inappropriately at $5 or so, and most importantly because of the content of the apps. As research for this post, I've just bought 'Sexy Ladies Angelina 2008', which is an entirely typical app, and it's disgusting - not because it's treating a beautiful woman as an object to be sold, although it does that too, but because it's US$4.99 for an application consisting entirely of 15 pictures of Ms. Jolie, complete with next and previous buttons. That's it. That's all there is, for $4.99.
If it was just that one app, I'd call him an idiot, but not an abusive spammer and scammer. There are hundreds of them, literally, all targeting different 'Sexy Ladies', all presumably exactly the same program with a different name and different photos. He got kicked out of the iTunes store, officially, because there's no way he has permission from the owners of the photos to sell copies of them, but frankly, he should have been kicked out - and he should be kicked out of the Android Market, permanently - for being a spammer, and scammer, and a bastard.
Oh... must remember to refund the app. Don't want to give the bugger any of my hard-earned!
IndiaNIC are probably the closest to Khalid, although close is a relative term. They've also resurfaced recently under a new name, presumably because they were no longer welcome using their original account, and they are now known as "Apps Publisher". Their scam is simpler than Khalid's - they publish ebooks on the Market, one app per book, and charge a small fee for each one. Not much of a scam there, except for the fact that the vast majority, possibly all, of the books they're selling are out-of-copyright public domain books. In other words, they're selling free books for a dollar a time, and flooding the market with well over 100 of them. More annoyingly, a lot of them are religious books, which deserve more respect than they are given.
Keytel Co. Ltd. aka Shin Hiraide aka Negroni - let's face it, publishing under multiple names, particularly at the same time, is a pretty clear sign of a spammer. Well over 200 apps, as usual all identical with different media, as usual almost certainly not paying any royalties or licensing fees on the media in question. In this case, their single app displays photos when you finish a call, which seems pretty pointless to me anyway, and the only difference is which photos it displays. A twist here is that the apps are all(?) free, which makes it hard to work out what they think they're going to achieve, really.
M STAR LLC are an interesting case. They have a number of 'calculator' apps, each domain-specific, like a Probability Calculator, a Concrete Calculator, a Piston Speed Calculator and so on. They could probably be combined into one app, some are free, some are not and, well, they're not really all that spammy. What makes them spammy is the fact that once or twice a week, at least, they push out updates to all (or nearly all) of their apps. Since updates show up alongside new apps, that has the effect of getting their apps into users' views a couple of times a week. I really really doubt that their Probability Calculator was so buggy that they needed to release 10s of updates for it...
MGeek, UK Android Apps and Browser are three developers who are effectively doing the same thing - releasing simple wrappers around third-party websites (often the 'mobile editions') as individual apps. In many/most cases, they are also using the name and/or logo of the site they're wrapping without permission, giving a false impression that these are official apps from sports teams, websites, news outlets and so on.
These are not the only offenders, but they are the most obvious ones I've seen. The Android Market has many problems, some of which may be solved or at least eased with the upcoming 1.6 release - but it seems like spam will be around for at least a while, and will doubtless expand if/when the Market grows and there is really serious money to be made. While the openness of the Market is a major bonus, as I said above, a bit more enforcement would certainly not go amiss. We don't know how many genuinely pornographic, malicious or otherwise obviously 'evil' apps are blocked or banned, but I'd say it's not quite enough - yet.