[zifnab06]

I have a few domains I don’t host public-facing websites on - they’re used for either email, or internal things at home, or just hosting txt records.

There’s no sane way to validate a domain isn’t in use.

[detaro]

I'd argue that a "buy this domain! offers start at $1500" parking page and no e-mail or other DNS records set up, over years, is a pretty good indicator you're not actually using a domain.

[Can_Not]

Also the fact that you exceed some personal limit (or limit per legally registered company), let's say 25. For example, the general case we're all talking about, a company with 10,000 domains on sale for minimum bid of $2,500 would exceed 25 and would have to pay the penalty on all but the first 25.