In my opinion I think it would depend on the desire of the Dom/Master, some may like the idea of wearing a collar, while another Dom/Master may find that it may be an insult. Personally I wear a spiked collar and I haven't received any criticism for it.

On the note of a "real Domm/Master" It's my own opinion to that clothing isn't what makes them are true Dom/Masters, it's how they use the skills they have learned and mastered to make an experience enjoyable for both them and their sub/slave. All the while having the desire to better themselves. But this is just a personal opinion.

I don't really understand why people get that in their heads myself. Collars are not a submissive only item. I wear collars all the time, and I'm usually the dominant. I look at it this way: Who's more dominant, the one not wearing a collar while I control them, or me, wearing a collar regardless of it's notation of submissive being, and dominating them. What I wear proves that, even if I'm wearing the collar, I am in control. :3