

You can check whether you’re clean with a toilet paper, if you’re unsure. But I did so a few times at the beginning and never had stained toilet paper (so long as I didn’t stick it inside, I guess), so I don’t bother anymore.
In particular, you also feel cleaner when you regularly use a bidet (like you’re freshly showered), so that also makes it easier to feel when you aren’t clean…
I use a hand-operated travel bidet, so it’s exactly as overpowered as my handshake is firm. 🙃
More seriously, I did say not everything past the sphincter will get cleared out. But yeah, I believe it is generally possible for humans to relax their sphincter, so if you angle the beam right, that should do the trick…