That's just a little extra I do sometimes, it's not really important. Just to see if that user shows up in search results for an item they downloaded from me. They may not show up in initial searches which is why I do several 'Find more results' so it may take 20 mins overall. I usually search several of the items they downloaded from me also.

If the user shows up in search results, it is much easier to browse them. Of course no guarantees. But as I suggested earlier, browsing from upload window is the most difficult.

Since I share so much I am a little fussy about freeloaders. Personally I don't mind them grabbing a few files. But if they are grabbing a large amount it might make me wonder since they are using up my upload slots & my upload slots usually have a large demand. So if I cannot browse them I search for the files they have downloaded from me to verify they are freeloaders.
If I suspect it's someone just starting out then that's fine, as long as they are sharing what they downloaded from me.

One kind of freeloader: sometimes I can browse them (if only via the approach in top paragraph), sometimes they are sharing 'some' files, if only the files they downloaded that session (usually mostly mine lol.) But each time I try to download files from them, they don't download. I refresh the browse host result, discover they removed the files I attempted to download. This cycle repeats & repeats. ie: they are deliberately trying to prevent me downloading from them. I ban them in that situation. I've seen so many do this over past few months. It's highly annoying.

There are also those who clear their shares after each session. Thus only have what they downloaded that session. How do I know this? Made a note of their identity from previous sessions.

Of course not everyone shares what they just downloaded, they might check the files first before sharing. And some of these people may be sharing files but different kinds of files from what they are downloading from you. eg: might be sharing movies or pictures instead of the music they downloaded from you or vice-versa, etc.