Jill, I am very happy with my DNA test results.
I must admit to spending a lot of time on researching both my tree and my DNA matches. Too much time probably, but in the winter it is my main hobby, gives way to second place later on in the year for gardening.
I wasn't underwhelmed when I got my results back, I was overwhelmed. So many matches, was I connected to all of them, how do I go forward, why so many matches with USA testers, etc etc.
But on the very first page was a match with someone whose wider family I had been trying to convince for years that they had made an error in their Australian ancestor's origins.
No brick walls for me until several months in, but they are being broken away, bit by bit. The only problem with brick walls in genealogy is that when you break one down, you create two more in it's place.
Of my 130 or so 4th to 6th cousins I have positively matched with about 25 of them. Something tells me that if they and I had the right information and were willing to swap that information, I would positively match with a lot more, perhaps unlikely to break down many walls for me.
Of my many thousands of 5th to 8th cousins I have positive matched with about the same number, about 25. These are where the nuggets of useful information come from.
Xin, you say ''OK so I just ran through quickly and randomly picked two of the 5th - 8th moderate matches.. and this is the result. NO MATCH in my estimation.''
It is up to you to decide where the match lies - Ancestry are merely finding matching surnames in both your trees, they are not saying that Nancy Brown from Portsea is the same as your Brown from Scotland. Or that Rhoda Duncan from USA is a match with your Duncan from Scotland.
Have you entered all of your 7G grandparents? That is 512 names. Have they entered all of their 7G grandparents?
I know all 16 of my 2G grandparents surnames. I have names for 50 of my 64 4G grandparents. I certainly don't know all of my 512 7G grandparent names, though I do know quite a few of them.
If you or your DNA match have not got all 512 names, how can you say that you don't match with them?

Regards Margaret