Unpunished and brand sites make up most SERPs these days.
Yes, Penguin in particular seems to have had this effect, but a lot of webmasters (including me) have done quite a lot to overcome it, and in my sector a couple of older page 1 sites have slowly regained position. My own site - for years dominant on page 1 - was massively penalised, predominately for wholly organic links, and a lot of remedial measures (including a BIG disavowal) seem to have gradually restored it to its current postion in the top half of page 2. One of my main SERPS and business competitors has also recovered to the bottom of page 1.
The current results in my sector are therefore comprised of some unpunished sites - mostly, as you observe, not very popular (lacking in both backlinks and content) - together with a few of the older, better sites slowly rising from a long period at the bottom of the SERPS. I think my own site's position has also been helped by the failure in January of a business that locally started infringing my trade mark in 2010.
Traffic and conversions are not yet reflecting the gradual SERPS recovery (my site is still at less than 20% of 2011 Google referrals), and it isn't clear where the traffic and the business is now going.
I'll be submitting another disavowal in the near future - if clients can't find me it looks like every spammer and his brother can - but other factors are also coming into play. In particular, I think we ignore the mobile-friendly movement at our peril, and this brings a whole host of design and content factors in its wake.