In my experience, it is accurate. Google doesn't know "nicetry99", but it does know "octopus99", "octopus98", "octopus97", "hacker99", "hacker98", "hacker97" etc.
Anecdotal evidence might as well be no evidence. I'm not saying that you don't have a unique or clever idea, but it should be judged on its merits. This tool will be great for finding common passwords and variants where a system uses unsalted MD5 hashes; but it relies on known hashes, so for the vast majority of possible input strings that have no reason to be generated or indexed by Google it's ineffective.
