"PSA: For everyone who uses Pinterest, they recently started incorporating sponsored pins into the stream and very quietly (they sent an email, but you might have missed it) switched everyone's account to different settings to accommodate it.
What this means is that your Pinterest stream is no longer organic (based on who you follow and when they pin), but on "web cookies" that track your recent browser history. They use this info to deliver the pins they think you want to see, plus sponsored pins that are tailored to you based on the sites you've previously visited.
I don't know about you...but I don't like sites telling me what I want to see. I'd rather choose for myself and see the results organically.
GOOD NEWS: You can shut these settings off and switch back to the original stream.
1) Go to your pinterest profile and click on the gear icon at the top right of your main profile box. A box will drop down.
2) Choose "Account Settings".
3) Scroll down to the section labeled "Personalization" and choose NO for both options.
4) Make sure to hit the "save changes" button at the bottom, so it goes through!"
Most people DO NOT like the new stream (and the changes), so feel free to spread this message far and wide. It will benefit us all!