Chapter 5 of the IBC handbook states what the ideal show betta is:
"THE IDEAL SHOW BETTA
The ideal show Betta is in excellent health as shown by its faultless condition and vigorous deportment. The body
and fins are unblemished. There are no body scars, spots, and missing or misshapen scales. Fin rays are straight or
smoothly curved. Fins are held rigidly erect and gills are fully flared. Movement is continuous and aggressive with violent
response to any intruder.
The ideal show Betta presents nearly mirror-image symmetry above and below an imaginary mid-lateral
line. This Betta is well proportioned with respect to fins and body size. The body is smoothly tapered toward the
caudal peduncle. The dorsal fin approaches the anal fin in shape, width, and size. There is a 180-degree spread
between first and last caudal rays. The outer margins of the dorsal, caudal and anal fins trace a continuous
circular contour with no gaps between fins. Fins are broad and overlap at the edges. Secondary and tertiary
divisions occur at even intervals along the lengths of fin rays.
The ideal show Betta exhibits brilliant coloration of uniform density. In solid color classes there are no off-color
washes in the fins and no blotching or speckling of unwanted colors on the body. Patterned types have dark and bright
colors in shades that produce the highest contrast. The overall appearance of color on this Betta is one of vivid, sparkling
beauty.
So yes, there is such thing as a show quality betta; if it doesn't meet the standards of said show then it's not of showable quality.
This is a GENERAL description. The handbook then indicates qualities for every class.