I'm sure some skimmers are worse than others... but I've only ever used 1 hang-on so I can't really speak to which ones.
I have had just about every skimmer I have ever owned go crazy at some point or another for seemingly no reason (not always causing a flood, but certainly not skimming properly --either over or under producing). Oils on your hands, different foods, using two-part epoxies in the tank, are all things that can mess with the bubbles in your skimmer. If you've never had a skimmer go crazy, you're lucky... a Coralife SS I was running before emptied 1/3 of a 30 gallon tank onto the floor over night (only stopped when the pumped started grabbing air).
Some skimmers are designed to create back pressure when they get full so that they essentially shut down bubble production and usually won't flood. Unfortunately, many of the widely available hang on the back types are poorly designed because they are made as a cheap solution. Either they are being installed on a smaller tank (and there is a limit to how much people are willing to spend on one component if the whole tank is smaller) or as a cheap/easy/quick way to add a skimmer to a larger tank (cheaper than adding a sump). There are exceptions to every rule and I've honestly heard mostly good things about the aquaC (but have not owned one).
and I will entertain offers.
