@unknownuser said:
do you have podium installed by any chance?
bool tools & sub/smooth have complications with podium but it can be sorted out..
I don't have podium. Here are the plugins which I have tried that also just don't show up in Sketchup on either Mac:
-btm sculpt tools
-bool tools
-subdivide and smooth
-extrude tools
-round corner
-clf shape bender
-draw helix
-offset
-tools on surface
-unfold tool
-Fredo Scale
-sketchy bevel
-sketchy FFD (seems to have trouble working like expected)
-soap skin bubble (works only if i force it to load using Plugin Ruby resources)
There are more plugins which will not load either. It seems to be about 70% won't load. The other 30% show up in Sketchup, but only half of those seems to work right.
OS X's Sketchup has two plugins folders that I could find. I tried both. I tried just adding one plugin at a time. I tried repairing permissions. I tried the trial pro version, I tried praying to the dark Gods of 3D…okay i didn't really try that last one, but I'm really stuck—maybe i should. 
I do have some plugins that DO work:
-curve stitcher
-weld
-bezier
-tube along path
-FFD (kinda works, i can't load any toolbars for it only right click options work)
-Soap Skin Bubbles (has to be force loaded by Ruby Resources plugin—each time i launch Sketchup)
-uuhhhhh… i guess thats all I am able to use right now. 
