Perhaps the biggest source of misunderstanding between those who are British Traditional Wicca (BTW) and those who are not comes when a BTW practitioner tells someone who is not that they aren't Wiccan. It is certain to result in hurt feelings. And it often leads others to think that the BTW are elitist snobs. So let me see if I can explain it so that non-BTW can see what the issue is and why what they are saying has a certain truth to it.
As we all know, Gerald Gardner introduced Wicca to the world in 1954. As it was originally conceived, Wicca was a oath-bound, initiatory Tradition. That means that no one who is not an Initiate of Gardnerian Wicca would have been taught any of the true teachings of Gardnerian Wicca until after they were initiated and had taken a solemn vow not to reveal those teachings to anyone who was not also an Initiate. All of the other BTW Traditions also follow this custom. So unless one has undergone initiation into a BTW Tradition you really have no idea how Wicca (as it was originally conceived) is practiced.
So to many BTW having someone who has no idea what Wicca (as Gardner gave us) really is calling what they do Wicca feels to them as if it detracts from the hard work and effort that many of them have put in over the years to maintain Wicca as an oath-bound, mystery Tradition.
Now some of you will say that you have found Gardnerian or Alexandrian BOS on the internet, or you've read Lady Sheba's book, or you've read Aidan Kelly's book, or the Farrars and therefore you know how BTW practice. But do you really? These people took solemn oaths not to reveal their teachings to anyone not an Initiate. Do you believe that they really violated those oaths? And if they violated oaths given to those they were closest to in their covens, why would you think they are being truthful to you? Anything can claim to be a "real" BTW BOS, but you have no way of knowing whether that is true. Would you consider yourself a neurosurgeon and operate on patients just because you had read a book about a neurosurgeon?
At this point what generally happens is that the non-BTW becomes angry and feels that the BTW individual is saying that their path is not valid. But that isn't what is being said at all. Actually they aren't making any claims about the validity of your path. They are simply saying that it isn't Wicca because your practices are not the same as what BTW do. And according to Wiccan teachings, Wicca is orthopraxic rather than orthodoxic. In other words Wicca is a set of specific practices rather than a set of specific beliefs. They simply would rather that people would pick a different name for what they do, such as Witchcraft, rather than Wicca because using the title of Wiccan isn't accurate.
Now, not all BTW feel this way. Many of us, myself included, believe that this horse is well and truly out of the barn and we can't put it back again, even though we'd like to be able to do just that.
So not all of us will say anything if a non-BTW Initiate wants to call themselves Wiccan. But some will. And that's why I'm trying to explain where they are coming from so that perhaps hurt feelings can be avoided. Remember if someone says this to you they are not saying that you are a bad person or that your spiritual path isn't valid and important to you. All they are saying is that the word you are using to describe your path is inaccurate and another term would be better.
So when a BTW challenges someone on their use of the words Wicca or Wiccan they're not trying to be an elitist, they're not trying to belittle you, and they're not trying to say your path is invalid. They are simply saying you're applying a name to what you do that isn't accurate. Hopefully understanding that will help prevent hurt feelings and start building some better bridges of understanding between the BTW and those who are not.