I just wanted to say, excuse me if I am acting like I know everything! I really don't... ;)
It is probably very true that there are some zappers made of junk, so it is very good to get one that is recommended and isn't going to fall apart on you, as well as one you have heard actually works. I just haven't heard of any of them specificly, so I thought maybe you were putting them all in the same boat. :D I guess not.