Pinterests recommender system algo (picture suggestions) is flawed&#x2F;broken. It shows you always the same pictures, of the same k-mean group.<p>And their nag screen to login&#x2F;signup is as annoying as on Quora. Btw: Has Quora completed their pivot already, they joined YC like a year ago? <a href="http:&#x2F;&#x2F;venturebeat.com&#x2F;2014&#x2F;05&#x2F;09&#x2F;meet-the-oldest-y-combinator-startup-ever-quora&#x2F;" rel="nofollow">http:&#x2F;&#x2F;venturebeat.com&#x2F;2014&#x2F;05&#x2F;09&#x2F;meet-the-oldest-y-combinat...</a><p>Glad to see <i>pg</i> doesn&#x27;t like the nag screen either: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=5217449" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=5217449</a> (full context: <a href="https:&#x2F;&#x2F;www.quora.com&#x2F;Why-did-Quora-join-the-2014-Y-Combinator-batch" rel="nofollow">https:&#x2F;&#x2F;www.quora.com&#x2F;Why-did-Quora-join-the-2014-Y-Combinat...</a> )