Speaking as a User, not an Admin (statements made here are my opinion not policy).
I'd really appreciate it if more care could be taken when tagging MOCs. I use tags to find things I'd like to build but it gets very hard when designers go crazy and tag things with unique tags or spelling errors.
If you tag your MOC and it's the only instance of that tag (the number next to it says 1) then one of three things:
You may have spelt it wrong, spelling is not my strong suit so I'm pointing no fingers, but if it's a common term and you're the 1st then double check your spelling.
You may have used a less common term for it, for example "The Simpsons" vs "Simpsons". Ignoring the argument about which is correct you should be aiming to get the same one the majority of users have used, otherwise your MOC won't appear when someone searches using the opposite one that you used. Having multiple terms for the same thing makes it harder to find them all and hurts your chances of being found.
Your tag is probably useless. If it's something so obscure then a user will probably never look for it anyway making the tag moot. For general searches the system checks all info anyway so if that term appears in MOC name or description then a general search will find it, no need for a single use Tag.
At this point, with something like 15k MOC's any useful tags have almost certainly already been used. If your tag isn't useful then I question why you use it. I just want to be able to find your awesome MOC's, please help me.