I just moved this from elsewhere to this New Tool: DynamicPSF thread since I see the subject of rotation angles 180 deg apart is being discussed. I don't I agree with the conclusion above that this just concerns a a few outliers at least for my data that may not be the highest SNR. IMO, the problem is the fundamental degeneracy in the elliptical representation that is causing my population of stars to split roughly equally between near zero and near 180 degrees rotation angle. Perhaps it would help for DynamicPSF to also report (with any noncircular option) the 'relative rotation angle' for each fit WITH RESPECT TO THE MAJOR AXIS OF THE ELLIPSE which would then be a more consistent and meaningful measure with which to discard outliers, even in the context of the 180 degree ambiguity in the rotation angle of the major axis itself. But I think some scheme might also be devised to resolve the 180 degree ambiguity (due presumably, as Juan suggests, to the randomness in the initial star detection location) in the major axis. That would probably be more complicated; perhaps, some kind of clustering algorithm to identify a single major axis (same sign rotation angle) out of all the reported axes from the individual fits.
The following probably belongs on the wish list topic, but what I'd really like beyond fixing this degenerate sign-of-the-rotation angle problem is another layer that would analyze subs (better, multiple subs) to generate maps of FWHM (curvature), aspect ratio, etc. to provide detailed analysis of image quality -- plus maybe a sorter that ranks subs in terms of those qualities. That would be a very useful addition, IMHO.