Unfortunately to spot and be spotted, one must wear something large enough to be really noticable at a distance. If you only have a small mickey head on, most people won't notice that unless they are right next to you in line, or sitting near you at a restaurant or bus or something. Most of the time at WDW you are not up close with people--except in lines. Walking around it is hard to spot Dis-ers unless they are wearing something large that really screams DIS.
I have spotted and been spotted, lol, but it always involves something large. One Dis-er I met wore a large loopy curly green ribbon hanging on her lanyard (not the little curly ribbons). I spotted her walking twenty yards away. Last trip I spotted a woman wearing one of the Dis fanny packs--the whole thing is lime green and says "THE DIS" on it in four inch high letters. Others I have seen wore big lime green pins that said THE DIS.
Lots of "regular" guest wear lime green shirts (just easy for a family to spot each other in, I guess) and there are a ton of lime green lanyards out there. (only one that says THE DIS on it though--but those are hard to see unless you are right up near someone). I also saw a ton of those lime green waterproof passholder things, but they were for some company I hadn't heard of that I think was having a convention nearby that week.
If you want to be seen--make it really noticeable. My problem is, I always forget to wear my pins/ribbons when I leave the room each morning. LOL!