It sounds complicated, but is rather easy (and unique, sic those other clients, boys!).
Imagine you search for "amule source code" and get 3 hits (that is: unique files with unique MD5s):
A: "Amule Source Code.zip"
B: "source code of the amule client.tar.bz"
C: "amuleus sourceros codeos des internationals espanol del sol arriva!.txt"
(i made up the last one, i don't speak spanish, please don't be upset, it is just an example)
Imagine that A, B, and C each come with two additional names:
A2: "Free Emule client source.zip"
A3: "open source client.zip"
B2: "Sex, Porn, Virus.exe"
B3: "Amule Source for Linux.zip"
C2: "Olala, los torreros!.txt"
C3: "Juanitas de Madrid.txt"
Now, here is the catch: Compare your original search statement to _all_ names of _all_ files and find out how often your keywords show up in the names people give to one and the same file. Also take into consideration how _many_ people call a file by a certain name and how _much_ of the file they already have (a seeder should know a fake). Furthermore: if one and the same word(s) turns up in _more_ alternative filenames than _any_ of _our_ keywords something must be wrong (normaly, you would have a B4: "Virus construction kit.zip", B5: "Porn! Best ever.avi" and B6: "SEX SEX SEX.rar" and so on).
File A is obviously a correct file since at least one keyword shows up in _all_ the filenames.
File B may or may not be a fake since there are filenames where none of the keywords apear.
File C must be a fake (or an error of the search engine or the server, in any way useless) since none of the keywords appear in any of the alternative filenames.
I am not a good coder, but i think if you get this a bit grainier by using the numbers amule already _knows_ about the search and the results and the numbers amule _learns_ when it starts downloading then you could compute a "confidence factor" or "anti-fake indicator" to show as a column in the download subwindow. So, one would start files A, B and C with "white" indicators and - after a few minutes - see C faltering to "Red Alert", B going to yellow and A gaining a nice, green color. One would kill B and C and hence eliminate stress on the net, his own link and his computer. And it would whiten the knuckles of the emule, lphant and MLdonkey devolopers, because _they_ (or their supporters) didn't came up with it, hi hi...
Quakemire