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Some valid comments here, but I'd generally have to agree with Ron - IF the domain really has authority (solid, trusted links, isn't spammy, decent traffic, social signals, etc.) and IF that domain is relevant to your topic, then it could give you a solid boost. As @KempRugeLawGroup said, though, there are cases where Google may not pass the authority of the site after an ownership change, especially if you completely overhaul the site and it's an entirely new topic. Unfortunately, there are no guarantees. A lot of this is at Google's discretion. If you bought a high-authority site about bass fishing and then turned it into an affiliate site for WordPress templates, and the domain was "bobsbassfishing.com" and 80% of the inbound anchor text was "bass fishing", then Google's going to catch on pretty fast. If you actual sell fishing products and keep the brand, but slowly redesign and add new, relevant content, then it's entirely possible that old domain will work in your favor. If you just buy an old domain and then 301-redirect to a current or new and barely relevant domain, then it's at best a crap-shoot. That game has been played far too much.