what types of penalties are there?

[whatson]

As we all know Google can penalize your site for various reasons but I have seen several different penalties, presumably for different tactics.
There is the grey bar penalty - when your site is banned
The white bar penalty - when your site becomes PR0
And the reduced PR penalty - this is when the homepage has a PR of about 2 or 3, and every other page in the site has PR 0.
Why does Google have these different types of penalties?

[anallawalla]

the grey bar penalty - when your site is banned

Really? I thought that the grey bar means that your site is not known to Google.

[whatson]

Grey bar means your site is not in Googles index. This maybe because it is a new site and is not in the index yet, or it does not have any links to it. Or it has been banned. On occassions there are sites that are in Google that have a grey toolbar, apparently this is because they get indexed by the toolbar.

[ciml]

There's also the 'can receive PR from incoming links (and rank well as a result), but can't pass PR out' penalty.

> Why does Google have these different types of penalties?

I guess that they just feel that some sites should be removed, while others are just involved in link manipulation.

Also, by having a number of different types of penalty, it's harder for people to see how they work and then avoid them.

[James_Dale]

'Reduced PR' penalties are often given to sites using multiple domain interlinking. Domains hosted from the same IP can get you caught out in this respect, as can careless traces of relationships between sites. Whois information may also be a factor.