OK, I went around taking some pictures to show you. I have tomato seedlings that are deteriorating from mite infestation. My best guess right now is they are Broad Mites and not TRM's (tomato russet mites). They are microscopically invisible so I just go by the way the plants look rather than trying to see them or ID them.
See what you think. And maybe other folks could weigh in if you see (or NOT see) similarities here, too. I'm afraid I'm in "spot the infested tomato seedling mode" and might be seeing mite damage everywhere I look, regardless.
The faint russeting -- brown-looking hairs, especially from the soil level up and then concentrating on the terminal leaf bud, rather than the pristine white/translucent downy hairs of healthy seedlings -- are the first suspect indication.
If you click/tap on the image, you will open a zoomed 2MP version.
The top LEFT photo shows seedlings that I am treating with home made oil/soap/alcohol mixture. The reason I asked about the oil treatment with yours is that I though I saw similar translucence in the leaves and oily sheen.
The other photos show seedlings at various levels of infestation. Ignore the white blotchy marks -- they are there because these are special, variegated leafed variety. I also have a potato leaf variety here. Focus more on the dark blotchy marks and slow crisping along the edges.
Once the topmost growing leaf bud has been blasted, tomato seedlings that are trying to recover from infestation will grow a new side shoot from a lower leaf node, and if that doesn't get infested and taken down as well, they will recover (or they will try again and again from a lower node until they exhaust themselves). The seedlings that I'm not treating are nestled among pepper plants that recovered from its infestation after releasing predatory mites, and some are trying to grow new shoots.