I think you may be just a tad paranoid.
With millions of "G" network clients, it is quite possible to have multiple u/l going at the same time of the same file.
I once d/l a file from a dialup host I believe. After I checked the file and put it into my sharing folder. I had 10 u/l going at once on the file. It must have been popular.
There are some that don't like leechers, and I am among them, but we all started with very few files to begin with and slowly build our libraries. If they are a legitamate "G" network client I leave them alone.
The only times I have removed a host is when they start bumping other hosts to get ahead in line for the u/l. Normally none "G" network clients.
Yes some will automaticly reconnect especially if your the only host with the file. It can be annoying at times I agree.
There may be many reasons why you cannot browse a host for example if they are firewalled, or if they have chat disabled it makes it rather difficult. It doesn't mean they are not sharing.