A hint, is when a download offers a "stub" installer.
I downloaded an Applian version of FLVPlayer, and it was only 300KB or so.
A scan on that using virustotal.com, had nine of forty two AV programs
detect a problem. Not a bad problem, but that "adware" was involved.
The stub installer, then downloads a ton of other junk.
If your AV was good, it is supposed to detect the crap as
it comes into the computer.
it with 7ZIP or a hex editor, and look for signs of crapware.
When the software attempts to hide things, that is a hint what
is hiding and waiting for you later. UPX packing is used more
often for mischief, as opposed to being used just to save
download bytes. And stub installers are not particularly a good
I judge software by its characteristics, before clicking the
installer when it arrives. If it is not very trustworthy looking,
then I have to do a lot of extra work to find out what I have got.
This is why I have "zero" toolbars so far. Never trust anyone.
Especially the download sites that bundle their own crapware,
on top of your download.