Here is what Google had to say about it themselves when they instituted their new policy back in 2006:
"As you may recall, we began incorporating advertiser landing page quality into the Quality Score back in December 2005. Following that change, advertisers who are not providing useful landing pages to our users will have lower Quality Scores that in turn result in higher minimum bid requirements for their keywords.
We realize that some minimum bids may be too high to be cost-effective -- indeed, these high minimum bids are our way of motivating advertisers to either improve their landing pages or to simply stop using AdWords for those pages, while still giving some control over which keywords to advertise on.
Although it is counter-intuitive to some who hear it, we'd rather show one less ad than to show an ad which leads to a poor user experience -- since longterm user trust in AdWords is of overarching importance."
It was Google's way to fight "garbage" landing pages as they say. BUT, I have had the same thing happen to me and I was providing what I felt was a great landing page, plus I was making A LOT of money from those keywords at that time. Here is what I did.
I simply bought a new domain for that landing page and redirected it to that domain. Google slaps the domain so you won't be able to use it for that same landing page ever again no matter what the new directory may be. They will remember. If you get slapped again buy another domain. I did that a couple times and now a campaign that was previously super slapped two times is left alone to bring me profit everyday.
I can't say this will work for you but if it is a profitable campaign with a good conversion ratio for you $8.95 for a new domain should not be a problem, even if you have to do it twice.
If you want to get technical, here is some more advice on how to avoid it straight from Google and my personal experience as well.
1) Don't use cloaking methods on your pages. Google will slap you if they figure it out.
2) Use little if any adsense blocks on your landing page. Google is crashing down hard on this due to all the worthless made for adsense sites.
3) Make sure ALL of your keywords in a given campaign are relevant. Break them up into smaller adgroups if you have to because you will have a better chance.
4) The best way around all of this is if your product or service would do well on a mailing list, create a lead capture page instead. Google very rarely will slap a lead capture page because you are providing information or the ability for a person to get information. Just make sure on the lead capture page you tell them what you are going to provide and make it keyword relevant.
I hope this helps. Ultimately Google can and will do what they want. Just use this experience as a way to profit even more. Your competition will likely give up. You won't and thus the slap could be the greatest thing to ever happen to your business. :-)