It is frustrating. I have 2 sites that are a bit "younger" than 8 years - 6 and 7 years old respectively. Never engaged in blackhat / greyhat / whatever for either site. Both got hit by Penguin 1.0 when they were 5 and 6 years old respectively. Never recovered to this day - in fact, they just slipped away a few spots at a time, from all the "fly in the ointment" links they win. They get loads of spammy links ...directories, aggregators, sub-sub-sub-sub domains from obscure Brazlian domain names and the like. There's so much link "detritus" that keeps coming in when I see latest links on GWT. I think they are simply a victim of their success. The more successful a site is, the more it's on the radar of scrapers / spammers, the more likely it picks up these rubbish automated scrapings. They DO win a lot of useful links too - links that give me genuine referal traffic - perhaps even Google may look at those kinds of links as spam too?
I launched 2 new sites late last year to "replace" these sites - the new sites now outrank the older sites, but the new sites don't really rank anywhere useful for me to make any money. I'm also now reticent to even try to make these a "Google success" - what's the point? It just puts them on the radar of spammers / scrapers. The older sites rank lower than the newer sites, yet the older sites make more money from non-search repeat traffic. An example of the balkanised web here - not visible to Google, but I have my own little "subculture" of customers / visitors who have bookmarked / recommend these sites.
The old sites still rank #1s and #2s in Bing / Yahoo! on popular keywords but that only brings in a small amount of traffic.
I've given up on the concept of launching a site in the hopes Google will love it. As mentioned, when Google do love it, spammers / scrapers come in and tank it. Not really neg-SEO I'm talking about here - I don't mean they do it deliberately - they do it inadvertently. I operate in niches that won't win huge authority links to protect them from these spammy links. I guess I need to go "proactive" to win such authority links....oh but wait, Google don't like guest posts or advertorials....just need to sit and wait... :) - no thanks, Google, there are 500 other things I could be doing to actually bring some money in rather than wait on wishes.