It mainly depends on whether or not you have a Google Account and are logged into it via Chrome. Incognito makes it so that none of your surfing history is actually stored on your computer... Your Browsing history, cookies, and other things should be clean for other users.
HOWEVER, if you are doing that searching while you are logged into Google Services (Gmail, Calendar, Blogger, etc) then Chrome will still send information to your Google Profile which is used to determine what ads they serve up to you. Probably not a very big deal BUT it could get weird if your wife starts seeing ads for "Get Laid in Queens!" when she's browsing her favorite recipe website.
Of course... Its also important to remember that the only incognito mode does is stop the browser from storing information on your actual computer. Your ISP may still be logging information about your visits and so, likely, is the website you are visiting. The best way to be clear of that stuff is to use a Tor client for browsing.
