I have a keyword ..lets say it's "Ford"...little did I know that when someone searches for "Chrysler"...my ad pops up!
Doesn't make any sense as to why it would show...but I guess G thinks its all good....
[adwords.google.com...]
A bid on "ford" will show for all inquiries that use the KW ford in them, but won't be matched to Chevy.
If there are words you don't want to show for, then do some Negative Keyword [webmasterworld.com] research.