fathom - 8:24 am on Apr 14, 2012 (gmt 0)
I know for sure there are ways to make spiders see irrelevant or spamy content and penalize someone but that implies there are issues with the site's code or configuration and can cause duplicate content, invoke error pages for valid links or generate new links and much more, all artificially created pretty quick with the aid of a botnet. But that's not up to Google to fix so I would make sure my site is clean of errors before getting into the conclusion it's the spider's fault.
The latter of the two... and maybe I misunderstood your meaning.
No you don't know for sure that someone can penalize someone else.
Yes you can do tons of things to penalize yourself.
Yes I know for sure that a code side-effect can be exploited in many different ways. If in doubt you can read other threads of people wondering how they endup with all sort of errors in GWT or just browse questions in the apache server forum. Just one mistake can make the spider see the planet through the site. That can be intentional or unintentional that wasn't my point and I've no idea how it relates to the google webspam team?
Or perhaps you meant code problems may exist but noone knows about them and so you want to see a step by step instruction manual how to do it in order to be convinced? From the angle I consider this may happen is not guessing.
Instead, you should be asking how webmasters react to these problems. Some blame the spiders, some themselves and others are in a limbo. IMO instead of worrying first if others do shady stuff, fix your own problems.
In the same paragraph you state... "Yes I know for sure" and "I've no idea".
Note: its poor form to use anonymous claims to bolster any position. You cannot determine anyone's level of knowledge, skill, experience, or wisdom nor the history or timeline of events.
I've seen people accidentally add disallow: / to robots.txt and blame Google for penalizing them.
Bottomline: believe half of what you see and a quarter of what you hear... then test it yourself more than once because false positives (and negatives) are common.