Spiritual dowsing is something which didn't really have much of a history before the latter part of the twentieth century. Prior to that time, dowsing was more focused on subjects like water and mineral locations with the beginnings of health dowsing just showing up.
As the century progressed however, for no obvious single reason, there was a surge of interest in using dowsing on non-visible and not-easily-verifiable subjects such as the exploration of ‘energies' of places and people and objects. This segued into dowsing about the universe and the beings which might or might not inhabit it or interact in some fashion with humanity.
In other words, dowsing changed from being a simple tool with a limited range of applications to a full-fledged multi-purpose activity reaching into any and every aspect of life. One of those aspects came to be known as spiritual dowsing.
However, it is not especially easy to define what exactly constitutes spiritual dowsing. Admittedly, there was a book published under that title, written by Sig Lonegren in 1986. The promotion for this said that it was written for travelers on the spiritual path who would like to see if dowsing can help them along their way. The book itself explores dowsing as a tool for locating energies found at ancient sacred sites as well as for health and healing.
As you can see, that covers a wide range of possibilities! And that is what makes it difficult to be precise about what constitutes spiritual dowsing and marks it as different from other dowsing applications.
Probably for most people when they talk of spiritual dowsing, they mean using dowsing to explore the invisible realms. So, for example, they will dowse about angels and archangels or perhaps something to do with their own spiritual goals.
The point is that the term is so vague as to not mean anything very much. Sure, each person who uses it means something by it, but not everyone has the same definition.
One of the reasons for this term still to be used today is undoubtedly because, for some people, it sounds like something which, if you do it, makes you sound a better person than someone who doesn't do it. In other words, there is a snobbery of sorts about it. ‘Oh, I'm a spiritual dowser. I'm involved in non-earthly things.' You get the picture.
Of course, some people will have made a detailed study about whatever it is they have chosen to define as spiritual dowsing and I commend them for their dedication to it.
I can't really say that it's something I am interested in, mainly because I choose not to make a specific definition about one area of dowsing. To me, dowsing is dowsing no matter what. I might be dowsing one day about the health and diet of one of our cats and the next day dowse about something invisible and intangible, like what is affecting our home to cause a specific physical response.
In other words, dowsing is just dowsing; which is making questions and getting answers. To chunk it up into different areas is not that useful, as the same skill set is required no matter what.