On the whole a person who “doesn’t mince his/her words” or who “calls a spade a spade” is regarded with cautious admiration. At least you know where you stand with someone who “speaks his/her mind” and who doesn’t “beat about the bush”. Our respect for this kind of person is perhaps evidenced by the fact that I instantly found so many phrases in English to describe them.
I think a similar high regard is expressed by the Spanish saying “no tiene pelos en la lengua” (He or she hasn’t got hairs on his/her tongue). This is a rather odd saying isn’t it? I mean none of us have got hairs on our tongues as far as I know, but on the other hand, not many of us beat round bushes too much these days either.