I only chose teams to put on the website that really use it regularly. We have a bunch more logos of the type others here describe that I could have chosen but that's dumb.

Two teams at Slack currently use Grain.

Behzod runs research and has been tweeting about his use of Grain a decent amount lately: https://twitter.com/beh_zod/status/1250900606073442305 https://twitter.com/beh_zod/status/1248740029901332481

Here's Jason from Podium: https://twitter.com/jregb/status/1250995517724585985

Here's Dustin from Lambda School (not one of the logos): https://twitter.com/dustint314/status/1250948975202426880

But the actual answer to your question of how is that it took a long time to build something they wanted to use. We've been building a version of Grain for about 15 months now, about 6 months on the product we just released and 9 months on a version we threw away.

Eventually we built up word or mouth of happy users that refer other teams. It's a grind to get real teams to adopt anything but it is possible with continued effort.

Whenever I see these, I suspect it's more along the lines of someone at Slack is using this product.

This is a correct way to interpret it. Just an email address sign up is usually used as enough justification to make the statement.

I guess we only have anecdotal evidence to go on here, but except for exactly one case I've always seen the organizations I work for get and wait for a positive response to their request before they display our logo. Does everyone else's experience really differ on this?

I have had exactly the same experience in my previous (and in my current) startup. I would never add the logo of a client without their consent. (maybe some don't follow that logic)

You aren't thinking like a growth hacker.

It is probably someone with a Slack corporate email address who signed up. At least, that is how most startups seem to define 'used by'...

Those are presumed fake, unless the other company posts a testimonial or signs a full name to the claim.