Soo, i've heard of it before...but the question is: does it really disinfect? And how could it damage the earrings (or gauges)?
I've never heard of that. I'm not sure that it is a strong enough base to really do any proper disinfecting. Your ears would smell clean at the very least. Save yourself the worry and use rubbing alcohol. It's not expensive at all. I have never had an infection in my piercings using it. I would clean the earrings with rubbing alcohol and then apply polysporin (triple antiobiotic ointment) until they healed. Now, I just use the alcohol to clean them.
Toothpaste typically has some abrasive stuff in it to help clean/ polish your teeth so it would not be ideal for cleaning jewelery. Even more so if we are talking about plugs. The scratches could be more inviting for bacteria resulting in even more of the infamous "ear cheese." I use a bit of alcohol every once in a while to get rid of the germs. Take them out pretty regularly (every couple of days) to keep them fresh. My face wash is mild so if I am wearing captives I will just work some of that through. Rinse thoroughly of course. If it is a new piercing or freshly stretched, sterile saline is the best way to go for cleaning the piercing itself.
The studies that have been done on removing bacteria say that it requires a bit of scrubbing which is why someone probably suggested toothpaste. It's not the toothpaste- it's the mechanical action of scrubbing that does the trick in dislodging the bacteria. However, toothpaste contains an abrasive that will scratch metal. It might not be the best long-term cleaning agent. Your best bet is to rub them in a small cup of soap and water or to use an alcohol prep pad to clean them.
I've always used hydrogen peroxide to clean my studs and captive ring bead hoops between wearings. It seems to clean them pretty well and remove any deposits that build up. (learned this from my sis)
It's often a good idea to avoid alcohol containing disinfectants...they tend to irritate fresh piercings and lead to longer healing times. You can probably use them to clean your jewelry, but you should rinse it off in water afterwards and let it dry in an environment that is as clean and sterile as possible.
