>>423No, -10 is the same as 190 in GIMP. If you rotate a layer or selection twice in GIMP, it will degrade the quality more, because it's a raster transform of all the pixels, though in more advanced image editing software (as in, definitely not GIMP), it rotates the layer but keeps the original layer data so you can rotate it as many times as you want without degrading quality. But every rotation in GIMP, if it's not a multiple of 90, makes the quality worse. To really see what I mean, try rotating something 10 times in a row (not by a multiple of 90), and you'll notice how it looks bad.
I use GIMP regularly and have been using it for over a decade. I do a lot of GIF animations that involve rotation. I think I know what I'm talking about.
There are very few things in life that I know a lot about, but GIMP is one of those things.