If you buy a dropped domain from Snap or Namejet, the backlinks seem to be worthless for SEO.  They are valuable for traffic if it's targeted to your site.  Go ahead and 301 redirect into your site because it's the traffic from the back links that is worth something.  I use the Google URL builder to redirect these names so you can see the domain the traffic is coming from.
Many individuals have the habit of collecting attractive domain names but never using them. If so, why not get rid of unused domain names and in the process, make some cash? It is important to understand the whole process of selling domain names. On the outside, the process may look very easy, but unless a trader is well aware of how the whole process works, it is not easy to find a buyer.
Current Craze: When PokémonGo was HUGE last year, my domain flipping friends (Matt of Handshakin.com is one) were all about buying domains like PokeStopNearMe(.com) and other related domains associated with the PokémonGo craziness. It’s like the day trading of the domain world. You’re buying domains during the hype and hope to sell them for a higher price quickly before the hype fades.

So the keyword planner came up with 332 keywords related to ripple, most of which can be used to inspire a domain registration related to ripple. Let’s go ahead and get some more ideas. We already know that ripple is another cryptocurrency. Let’s head to NameBio and explore crypto-related domain sales. We’ll use bitcoin for this experiment. I’ll type in “bitcoin” in NameBio search, select “show all” and then sort by price by clicking on the price column. Here’s what it looks like:
So, you paste the domain into here and click on the search domains button. This will show you more information about the pending delete status domain. In this case, you have to order by June 13th and today is the 10th. So, you have three days and you just add it to your cart as if you’re just buying anything online. Just check it off and click add to cart. It’s added to your cart and they will try to get it on your behalf.
Great article on what to look for when buying expired domains! I’ve looked at the domain and page authority of expired domains but haven’t checked if they are blocked by Google like you’ve listed. I haven’t pulled the trigger yet to purchase one (probably good that I didn’t since I didn’t do all my homework) but this will make it easier to finally go. Thanks for the great info!
If you’re serious about domain flipping, one of the best strategies is to buy expiring domains that auctioned on the market such as GoDaddy Auctions. Make sure you pick domain names that have good traffic, backlinks and SEO metrics, or domains with the generic niche. Expiring domains with a potential for profit can be found using BuycomDomain.com, this is a free website/tool that helps you sort through the domains by different metrics (age, traffic, backlinks, domain authority etc).

Buying and selling domain names is an exciting adventure that for some seems to conjure up images of finding hidden pirate treasure or guessing the winning combination on the next Powerball. Stories abound of domains that were purchased for $8 dollars 15 years ago being sold today for millions. Of course, that leads the more adventurous of us to wonder, “How can I do that?”
The practice of exploiting misspelled variants of popular websites for personal gain is known as typosquatting. Users who incorrectly enter URLs into a browser’s search bar may be getting more than what they’ve bargained for and end up on a squatted domain. We’ll show you how typosquatters exploit the simple workaday mistakes of internet users and how website operators and their visitors can...
Simply put, domain flipping is the process of acquiring a domain name with a motive of selling it at a higher cost to someone else. This is very similar to flipping houses or cars, the only difference being that you can’t do much to increase the value of the asset by ‘fixing it up’ and then turning it over for a quick buck. Acquiring a valuable domain name before it is tagged with a premium price is the key to a successful domain flip. Raymond Hackney, a domain investor and consultant, successfully flipped a .website domain (his first on a new domain extension) for a decent profit. Read all about it here.
I OWNED DOMPERIGNON.ORG, incredible, but true.  Lost it, back in the days when internet in India was not a readily accessible utility. And I was a casual domainer.  You had to go to a cybercafe. Did that late in the day, towards the expiry of the domain. No chance of renewal. The domain is now with the owners of Dom Perignon and is redirected to domperignon.com! 
Aside from places where you buy and sell domain names, there are some companies around that support the business of domain flipping. GoDaddy is one of the bigger names out there that does. There, you can not only trade domain names but also park those you’ve bought. The buying, parking and selling is relatively painless and all you must give up is a small percentage of your selling price.
If you want to participate in a domain name auction, there are several options for how you can list your domain. Once you’ve purchased a membership, you can choose a free and simple listing, or add advanced features to increase your domain’s visibility. See our handy insider’s guide on how to list domains for sale for more details about listing a domain.
They see a domain’s price tag and they can instantly tell whether it’s under or overvalued. This is probably the most important skill one should have in this industry. Neil Patel has an interesting related quote: “The most important thing to remember when buying sites is that you always make money on the buy, never the sell.” In order to successfully do this, you must be able to spot undervalued domains. This is what will ultimately translate for you into a handsome profit margin when you get the opportunity to resell the domain for its “real value”.