I hardly ever label angles, so I never noticed this before. But there seems to be a bug in Dimension Styles!
There is a place to insert a prefix or suffix for linear dimensions. But this prefix or suffix is also added to angular dimensions!
So, if you try to use a ' (foot) or M (meter) as a suffix, this suffix is also added to angles. Angles get labels like:
25°27'36"'
or
25°27'36"M
instead of:
25°27'36"
This bug exists in 2006, and after a check, I discovered it also exists in 2004. It seems absolutely amazing that this bug would have existed for this long, and no one has complained... Are angle dimensions really that rare?
The workaround is, of course, to override the dimension style when dimensioning angles. This is annoying, but is a better workaround than creating another set of DimStyles just for dimensioning angles.