How do you test a Portable Application to see if it's 100% portable or trace free?

[ComputerQuestio]

Yesterday, I went out and bought a 8GB Flash Drive that was on a special sale, only because I'm interested in Portable Applications.

Anyway, I enjoy the portable Firefox that comes with the U3 Drive and the PortableApps I installed. However I also really like Flock which is very similar to Firefox and based off of it. The problem is I just can't find that application in any of the official Portable Apps bundles or websites. So I did a Google search and found out that some programmers are working on making their own.

I read on one blog that the particular version of Portable Flock he installed left some traces on his computer, so it was on USB flash drive but not 100% portable when the drive was removed.

Is there a way to test if an application is 100% portable? If it does happen to leave some files/history behind, is there a way to check? Would going to Start --> Search and entering "Flock" as part of name a file, be good enough, or is it not that simple?

[ComputerQuestio]

For example, here's two versions of Portable Flock I found:

PocketFlock http://blog.itdunn.com/pocketflock/

And

Portable Flock 2 Beta 1
(on Flock Community Support website board) http://www.flock.com/node/62536
Which then has a link to another site http://stadt-bremerhaven.de/portable-flock-2-beta-1-englisch-downloaden/

[ComputerQuestio]

I also found a portable version of the Google Chrome browser at Softpedia
http://www.softpedia.com/get/PORTABLE-SOFTWARE/Internet/Browsers/Portable-Google-Chrome-Chromium.shtml

[Sylvander]

"If it does happen to leave some files/history behind, is there a way to check?"
The best way I can think of:
1. Say you use your Windows installation that's installed on a partition on your internal HDD...
To access and run the portable program [Flock?] held on some storage device [a Flash Drive?] that is accessible to that Windows OS...
And lets assume that the program HAS created some file[s] on the Windows partition [C:]...
And the problem is to find that[those] file[s].

2. What I do [that you could use as a method] is run the FREE version of SyncBack->[under WINE, within a Puppy Linux OS].
(a) Ideally, before ever running some program [Flock?] using Windows, I'd have made a SyncBack backup of the Windows partition contents.

(b) Then I'd reboot into Windows and run the program [Flock], then boot back into Puppy and once again run SyncBack to backup the Windows partition.

(c) During that new backup, SyncBack would display a list of "differences".
These are changes to the folders/files on the Windows partition [the "source"], as compared to the backup on the "destination".

(d) Since all you did when you went into Windows was to run the program [Flock], then shut down Windows to reboot into Puppy...
There aught not to be too many changes to the files...
And if any changes made were related to the program [flock]...
You would hopefully be able to spot those among the [few?] listed differences.

(e) If in 2a above, you had already run the program [Flock], and the files had already been made...
You would hope to see the CHANGES made to those files [date and time of access etc].