Image Maps: when do they become a problem?

[oliver_w]

As many of you know, image maps can be used to write invisible links (an application of spam), or they can be used to write legitimate links on heavy graphic sites.

I am wondering whether google has made any attempt to identify image map spam while spidering, or are they simply relying on Spam reports?

[jomaxx]

Can you please define what you are calling invisible links?

[oliver_w]

I am referring to, for example, a white image that is on a white background that is invisible to the user, but has image mapped links. Therefore, the links are invisible.