What should you say to someone who purchases these?

Here are some comments from the Plumbing subreddit:

Tell her the people that sell them say they're flushable. The people that repair plumbing say they're not. Who would you believe?

I mean, they are literally flushable so they aren’t lying. So are 18 golf balls and flip phones.

Had hammers, hockey pucks, hot wheels.. This is all in a retirement trailer park. Unsure how the hammer got to the pumping station...

There was a prison I used to inspect that had a major drug problem. Turned out visitors were flushing them down the visitors bathroom toilet, which was outside the secured visitors area. Drugs would wash up on the screens at the WWTP out back and the inmates that worked there would retrieve them. That was the end of inmates working in the plant.

I lived in a condo complex with 2 buildings and a central sewer line down the middle. The sewer line backed up and flooded the lane to our porches. The city came to rotor the line. One neighbor had flushed a dead 18” spider plant. It made it through the neighbors line but blocked up the central 6” line.