I've had the experience that glossy tends to be weak. I've seen some strong glossy too though, so it's not a rule.
That's probably more just because, the matte boards tend to be from production lines, where they follow the specifications precisely.
Cheap protos usually use cheap soldermask, and the cheap stuff just happens to be glossy, no surprise there.
There might be something about a matte surface holding flux better, and therefore something or other about paste coalescence. Idunno.
Tim