The new long Red Fox guide I checked yesterday definitely has angle built into it compared to 3 JK and 1 Parma guide I have.
I installed all of those guides on my Defender chassis yesterday. I tightened the guide nut to where there was a little bit of drag in order to not get a false reading due to slop. I made sure I didn't tighten the nut to the point that I pulled any angle out of the post that might be there.
The RF guide was flat on the plate but the other guides, with some variation, were off of the plate in the back.
I want to do on-the-track comparisons of the RF guide to the others so I tweaked the tongue enough so that all of the guides have at least a tiny bit of up angle. The RF guide, of course, has a little bit more than the others but from my experience, I don't consider it excessive.
AFAIK, it might be possible to compensate for excessive gude angle by shaping the guide braid so it has a bigger radius where it wraps under the guide at the front.