sg09,
That is interesting. So in that case, the results were changed to an extent by zipping the file. But both the zipped and non-zipped versions were at least detected.
Pondus,
Your reasoning makes sense. I just want to be sure the results can still be fairly reliable if a file is zipped. BTW, do you happen to know how AVs scan zipped files? I'm curious if they just scan them in "zip form" or if they extract them temporarily into some type of sandbox. Maybe this varies depending on the AV used?
Thanks to both of you for your replies.