Mask Scent 7 (Source)

I think I postulated that theory. It would depend on the equation for checking.

If they use something like this: d100 > (base chance + char mod - creature level) : success

Let's see if we can guess at what base is. Creature levels are, I beleave something like 1 to 75 (is there a single mob > 75?). This would be insta fail to normal folks so lets take a guess at some midpoint:

BC = 50, d100 > (50 + CM - CL) : success

lets add a ranger bonus in:
d100 > (150 - CL) : success

Now if that number is stored in an 8-bit, signed memory location (150 - CL) then we can get the following:

150 - 22 = 128. Why this number? in a computer it becomes 80h. It will be interpreted as -128 instead. from CL=23 on will be normal behavior but CL=22 and less will be insta fail. Obvoisly this is not the case so maybe BC is more like 35...

135 - 7 = 128. So CL 7 and less are insta fail. This looks more like what I see. Remember, CL>=8 will see standard behavior:
CL=8, d100 > 127 : always success, CL=7 flips to -128 and always fails
CL=40, d100 > 95 : small chance
CL=60, d100 > 75 : one in 4 will fail

Now get your camo and Bothan mods out...
d100 > (155 - CL)
CL=10, d100 > -111 : no chance, and this continues up through CL=27
CL=40, d100 > 115 : always success
CL=60, d100 > 95 : small chance to fail
This is all a big fat wopping guestimate, but it explanes why improving MS and Conceal might be making things worse.