Understood. However the problem I was speaking of doesn't relate to side light "bleed" resulting from flush mounted tubes. The light I was referring to is typically reflected directly off the face or clothing of a combatant from the 'shooter' end of the trit. tubes.
Please understand, this isn't a major issue and most will never see it. I am no longer working in a field where it would be a significant concern to me, but memories remain. I choose not to use them, but obviously countless thousands love them. They certainly have value and my comments were not intended to be "painted with a wide brush".
Some of the world's top name instructors and pistolsmiths (a few of which are close of friends of mine) wouldn't think of owning a pistol without night sights. I've owned weapons in the past that had them, and wouldn't reject a perfectly acceptable weapon just because it has them.
I see now that I missed half of your original question... As far as cleaning goes, I've never had a problem of any kind with cleaning solvents coming into contact with the tubes. While I wouldn't want to soak a night sight in solvent overnight, I wouldn't worry at all about scrubbing one with a patch soaked in most solvents. I typically use Shooter's Choice and have never had a problem.