this one baffles me.. a search for 'mustang for sale' in google brings up the following link from our website on page 7 - http://www.mustangtraderonline.com/?category=gt - but this page does not exist and hasn't existed for many years. when you click on it, it redirects to the home page even though there is NO redirect in the htaccess. can anyone explain this to me?
Well first of all the link you provided, is your index page.. the ?category=gt could be wrote also as index.php?category=gt.. so in essence it's not redirecting, you can see that by looking in the url after visiting it. And somewhere google must be spidering that link. From an old sitemap, old page that existed, a backup, etc..
when you say 'index page', what do you mean.. i know it shows my home page but that should be just http://www.mustangtraderonline.com. The sitemap or old page would have to be years old.. google doesn't keep stuff that long if the page doesn't exist, do they?
without investigating your code, I can't tell if a link to that page exists somewhere in your code. the index page = home page, http://www.mustangtraderonline.com/?bc=123467 or http://www.mustangtraderonline.com or /index.php?bs=3939393 any of those links would all go to your "home page" the bc, or category in your instance is a get variable, which used to get a specific category. But since that code is invalid in the url, it just loads the page. You can change the category or the bc to anything, and it will still load your homepage. I am sure somewhere on your website, that link exists. Maybe in an old sitemap, maybe another website is linking to that page, and google is crawling it, and since it "does" exist google will index it.
ok that makes sense.. still wondering why the 'plain' homepage is not ranked instead of one with ?category=.. never seen that before..