In my home I have two 50 watt (or equivalent) spots on a print, as well as the usual room light. The ceiling is white, walls are light, windows are south facing, and the print is on the east wall, so we're not looking at any reflections of windows in the glass or off the print. When I put a glossy and a matte 100% black print on the wall, under glass, and measure the dmax with my 1 degree spot meter from where I would be looking at the print, the matte paper wins the race; it has the higher visual dmax.
It's all about reflections and the type and intensity of the light. Glossy prints do not have a higher visual dmax in the real world in many normal interior display settings. The spectrophotometers have, in effect, perfect lighting and no reflections. There gloss prints win easily. In direct sun, its the same story. On the wall in typical home or office display, matte prints often if not usually will have a higher visual dmax.
With snapshots, you'll see people moving them around to get the reflections out of the way. That's hard to do with a print on the wall. So, my practice is to use matte under glass for wall, fine art display, but use glossy (B&W dyes usually) for brochures, cards, and snapshots.