Hi Di,
Unfortunately you do not say where you got that "mod" from. Since it's for moodle 1.9 I expect you downloaded it from the "old" modules and plugins database.
The plugins in that database have all been approved when uploaded there by their creators so should be free of anything "malicious". As for checking "sloppy" programming, I'm afraid there is no other solution than closely examining the code and making your own opinion.
If the real meaning of your question is "can I safely use that plugin on my Moodle site", the answer is to install it on a development site (a copy of your production site) first and use it there to make your own opinion. This is the usual procedure to follow when installing on a moodle site anything not coming from the "core" distribution.
Joseph