Adsense on landing page - any problem?

I've noticed a lot of BS sites that are obviously marketed using BH that don't have any adsense anywhere on the site, but sort of link around to other sites.

Is there any disadvantage to having adsense on the page you are promoting?

The only disadvantage I can think of is that the AdSense ads may lead your visitors off your landing page and to another site.

Absolutely as the poster above said, you will distract your leads and send them somewhere else. That's like having a coffee shop and selling coffee in a great spot, but renting out half your coffee shop to someone else who is also selling coffee. They will hurt your business. Bad example, but google adsense targets ads based off keywords on your page, so your landing page will be competing with other ads that target the same audience, some possibly even having a better sales ad.

That's all fine (Because I'm talking about a site like a blog, for example, where the revenue IS adsense) but I'm wondering if anyone knows of any possible "penalties" or flags that google may take notice of if you use grey techniques and the landing page has adsense on it.

For example, would google look more favorably at a landing page that does not have adsense on it? (i know, seems counter intuitive but I guess google knows people are going to try to earn with them no matter what anyways).

It doesn't even makes sense that you would get penalized for using Adsense, unless you had too many ads above the fold. Of course, the last few months have been straight our of bizarro world, so who knows?