Google Advises: Alt Tags Should be Descriptive and Accurate
Well, I was perusing the Google Webmaster Guidelines and came across this:
Make sure that your TITLE and ALT tags are descriptive and accurate.
Now, I’m always one to give the benefit of the doubt, so I’ll assume they meant the title tag in the document head. But there is no such thing as an alt tag. So, it seems that even Google isn’t immune to such mistakes as these.