If the third party in question does not have the trademark rights they claim, or it is not a very strong claim. In most cases, the third party will need their trademark registered with the US Patent and Trademark Office (USPTO). The USPTO website has a trademark search engine that you can consult. This may also require a cybersquatting attorney to help determine if the trademark claim is strong enough.
The easiest and least time consuming option is to 301 redirect the old domain to your existing site. This tactic obviously works best if both sites are in the same sector and are targeting the same keywords; otherwise, if you have a pet supply site and you buy an old Texas Hold 'Em poker site, a redirect probably might raise some eyebrows among the search engines. If, however, your site is brandnamepets.com and you buy onlinepetsupply.com and 301 redirect the domain over, you're inheriting a lot of topical and appropriate links.
I don't necessarily agree with some that dropped domains don't have value for SEO purposes but either way one thing you can do is to check out our tool for finding auction domain names (the tool has a database of domains available buy from GoDaddy and SEDO and also give additional SEO criteria to look up for the domains like backlinks, Compete data, CPC, Google stats, Alexa stats, etc. and there is also an option to schedule auction domain alerts so that you can be notified via email if a domain name meeting criteria you specify gets put up for sale) or you could use our tool fo domains dropping soon that shows all domains dropping in the next 5 days that way you can be ready to snap them up right away.
Instead of focusing on one domain name to sell quickly, try selling large volumes of domain names over longer periods of time. While this may require a more substantial investment, it will also return a greater profit in the long term. Remember, if you follow the basic principles of domain name speculation, there is good chance that your domain names will sell eventually.
Yandex replaced TCI with SQI (Site Quality Index). SQI looks similar to TCI, so I re-used the old TCI field, however all values are now the new SQI. Not all domains are checked yet, but all that had TCI > 0, are now switched to SQI and all newly added domains are also checked for SQI (starting today). Updating all domains will take a couple months.
So how do you develop that instinct? NameBio maintains a database of over 500,000 historical domain sales (as of writing this post). They have interesting filtering features by which you can narrow down domains by price range, date sold, keywords and more. Simply sifting through the listings on NameBio long enough will quickly develop your domain appraisal “instinct”.