As you might have guessed from the existing answers (of MAGolding and andejons, at the time I am typing this), there seem to be two truths to it -- the highly respected minstrel, and the -- basically outlawed -- gleeman.
This is because they are two very different characters. The minstrel ("Minnesänger") was usually already a nobleman and part of the court (albeit quite often of low rank). Performing well as a minstrel was like performing well in the hunt, in the tourney, or in the field, a sign of competence that earned the performer respect, a way to distinguish yourself among your peers. These were (usually) not men from the street that had earned their way up!
In contrast to this are the "professional entertainers" from the street, the jugglers, fire breathers, tavern musicians etc., who are, if you look at it closely, merely a step up from vagrant beggars. These are what the "not respectable" parts (and the "Jester's right" quoted by andejons) refer to. You definitely couldn't hit the Duke of Aquitaine over the head and get away with it -- it should be clear that we are looking at two very different "professions" here.
With time, musicians organized themselves in guilds ("Musikantenzunft", sorry there seems to be no English WP article on the subject), with only guild members allowed to perform in an area, and the guild having the privilege of playing on official events like weddings or funerals. It should be obvious that this was still something different from Walther von der Vogelweide reciting lyric poetry or singing about the crusades. ;-)