Back in time (2007 / 2008 / 2009) i also hand-registered dropped domain names and had successfully $xxx / $x,xxx sales, mostly because in 2007 / 2008 / 2009 domaining was a smaller and "nicher" business, then it was quite easy to find valuable domains there.
Right now when i say 99% of the dropped domains (excluding the backordered one) is crap, i'm optimistic. I still spend few hours, once in a while, looking at dropping lists. When i look at .com drops, excluding hyphens and numbers, i see no sense domains, typos, grammar errors, non sense 2-3-4 words combinations. However, it's not impossible to find domains with some hidden value. Traffic is, most of the time, very hard to find out but, again, not impossible.
Months ago i hand-registered a dropped .com with two generic portoguese words used by a brazilian company advertising campaign. I'm receiving traffic (50-70 uv / day) and already received few offers on it, still too low.
I registered this domain because i was fast and clever enough to understand this expression would be quite famous in Brazil (huge and growing economy), but it happened mostly because i have been practicing domaining (not constantly among the years although) for almost 10 years now, and i'm quite fast to recognize if a domain has potential or not. Then i do summary researches and if i find some corrispondences, i proceed with the registration.
I repeat, i'm excluding backordered domains because every day we have hundreds of clear $xxx - $x,xxx (sometimes even more) valuable domain names dropping and being catched by usual services (namejet, pool, etc), ending up to $xxx - $x,xxx private auctions. We also see LLL.coms dropping some days.
But the OP question was related to hand-registering dropped domains, so i think we should focus on them more than on all the great domains being auctioned privately by all the backorder services.