AFAIK, you can't. If you own a domain name and decide to drop it and then someone else picks it up, it's considered as new in terms of registration date. There's no history dates to check except googling for cached websites and searching for backlinks providing the domain hasn't been available for too long. Webmasters, not general population, don't want dropped domains for SEO reasons. A domain name that has been registered for, say, 5 years and has a PR of 5 and 100.000 backlinks will keep getting traffic, even if the owner has dropped his domain name. Now you enter and buy that domain and start building a website with different content. Google notices the content change and starts de-indexing your website and slowly removing backlinks and decreasing the PR. Which is perfectly logical, but some people believe they're going to lose something they never had. It's a failed logic if you ask me. There's absolutely nothing wrong with dropped domain names and if you find one you like, don't pay much attention to that unless you're one of those who don't quite understand the concept of a website. That's like you buying a used car with a full tank in it, being afraid the fuel in the tank, the previous owner put in, will slowly vaporize, and you'll have to re-fuel your car. Like you wouldn't have to do that if you bought a brand new car.
^ This is incorrect. You can check if the domain has dropped by checking the registration date with whois. If the domain is PR6 but was recently registered then you can be confident the domain dropped and was picked up again.
Registrars don't store whois history. That kind of information is 100% unreliable because it can't be proven.
besides also the wayback machine will tell differences and show if the domain was dropped for a longer timeframe before it was picked up
Doesn't matter, the registration date is part of the whois. Whois is available only for current domain registrations, not for registrations before current. To simplify, GoDaddy holds your whois information. If you drop that domain and someone else picks it up after two years with NameCheap and you check whois again, there is no way to see the whois information from GoDaddy because there is no such thing as whois history. Whois is not stored, it can only be harvested, which is still in the grey zone area and possibly illegal because it's considered data mining. Private companies manually collect registration data and then sell them to, say, domaintools.com which offers that information to retails users for a certain amount of money. Now you might purchase that service and think you have access to the whole history but that is not true. A domain name could have changed 20 registrars in the past 30 years but you only have information from the last 2 or most probably not even that. So there is no way, not in theory, to trace the whois history back to the beginning. Therefore the whole "issue" of name dropping is pointless.
As said before you might not be able to find out everything via the whois history but the wayback machine is a pretty good way to check and if you are lucky you will find information of the owner right on the pages but most time you will also be able to tell if a domain was dropped checking the blanks in the history.
domaintools offers whois history for a fee archive.org shows website history for free as to OP question: 1) people prefer buying long registered domains vs those dropped 2) the dropped domain is better then "never registered" because it might have some remaining backlinks and traffic AND it shows that you are not the only genius that might decide to register that name so there are some resons to believe it is good 3) the only reason you might consider to stay away from a dropped name that it may have some previous negative history resulted that it is banned from Google index/Adsense/etc, but there are ways to check that