Hi I looked into this more closely to see what was up with the shine sprite. The sprite used for the lube shine effect is in water.dmi . I don't think it applies at all for the invisible version of lube, which is used... nowhere that I can see? I assumed they were used in fake cleaner grenades but those don't even seem to use the *damaging* version of lube, maybe an oversight or I'm reading it wrong. It's definitely possible for a floor to be lubed with no indicator in the code but the overlay *always* shows up for like, 99% of the applications of lube I'm pretty sure.
The indicator itself is really bad though.
This is a picture of the animation of the lube overlay. The frames where it's visible last .7s, and the totally invisible frame lasts .5s. This is actually completely fine IMO, and the animation makes it more visible by having a moving component. If it stayed the same it'd probably be even harder to spot because...
... it's got poor visibility. This picture is of the overlay with no transparency. Notice how the 'shine' part of the sprite is actually pretty light grey instead of white, this means that on very bright tiles it'll appear *darker* instead of a brighter shine. This is because overlaying a darker color over a lighter color with transparency makes the lighter color darker. Also bizarrely, the inside of the tile is a dark grey. I assume this is to create greater contrast with the shining part, but in gameplay it often makes the tiles flash... darker? Which is very odd looking. Both of these issues are pronounced on lighter tiles, like medbay tiles or bathroom tiles. It's almost invisible against those. Visibility is ok against regular tiles and very good on dark tiles though.
Additionally, it looks pretty bad against any non-four-square tile. Like plating or carpet or grass. Not much for me to say about that other than it doesn't match up with what it's placed against.
With all the above points considered my opinion is that the overlay is very bad for its purpose and would benefit from being resprited to be both more visible against light backgrounds and to look ok on any tile type. A generic full-tile 'sheen' would look ok for this I think, but making it tile nicely might be difficult. I think it's easy to miss these details if you just look at the behavior in-game, so I hope that my post made what's happening here clearer even if people disagree with my conclusion that the sprite should be adjusted.