okay.. scenario.. I'm editing a Shoulder Pad using my spangly new mesh changy package (for want of a technical wordL) ... is it okay to do this and to use the final product in my renders?.. (the shoulder pad in question was an RDNA freebie).. is this in violation of some small print I've neglected to read out of the million readmes that are lying about on my HD? ..

as far as i know, as long as you dont distribute the edited meshes in any form, you can do whatever you want with them. If its specifically states in the eula that its for non commercial use only, you cant sell the renders either.

that's ok.. nobody's stupid enough to pay for my stuffL.. Thanks though. :D good to know I'm not p'ing people offL

I've always been under the impression that I can do anything I want with the files I've got as long as I keep them to myself and won't do any commercial work with stuff that is only for non-commercial purposes :)

If I wanted to put the results into freestuff for others (not likely but you never knowL) would I have to ask the original author for permission?

Yes, you would, unless the readme file specifically for that item specifies very specifically that you can create derivative meshes and distribute them. ;) I wouldn't take it too badly if they were to say no: it is, after all, their mesh.