Scaled monitors are sharp. The blur came from xrandr's default bilinear filter smearing the stretched screen. Scaling now uses nearest-neighbour filtering: at 200% every pixel becomes an exact two-by-two block, pixel-perfect like a low-resolution CRT; at 125, 150 and 175% the pixels stay crisp, some doubled and some not, which is the honest trade-off for a fraction (Windows itself re-renders at those sizes, which this desktop's pixel-measured drawing cannot). Pick 200% for the cleanest result on a high-resolution panel. Applied from Display Properties and replayed at logon.
curl -sL jacktulli.github.io/w2k | sh