Bluetooth problems were only the beginning of a labyrinth of issues when I upgraded from Mavericks to Yosemite.
It was a month long problem that was a daily obstacle.
This was the worst I've ever seen Apple in terms of Quality Check.
Seriously, I know what bugs are and these issues were not bugs.
Serious problems in every area of my system.
I finally wiped out everything on my local hard drive, didn't use time machine and just replaced the late 2012 iMac with a clean copy of Yosemite.
Since then, about 2 days ago, only positive experiences, in that the computer is running Normal.
Its smooth, no memory leakage, CPU boosts or bad graphics.
No breadcrumb trail of fixes like turning off dash, turning off iCloud drive, etc..
if you're at your wits end, and have your stuff backed up in some fashion
I recommend it - the clean format and install.
I'm using my bluetooth headphones now and doesn't seem to be a problem with safari flash player (youtube), iTunes, and a VLC movie, all of them seem to be in sync.
It took me a month of headaches everyday to come to this point but I'm glad I did, it wiped out all the wild card exceptions in terms of what couldve gone wrong. I want a working computer. Now I have one.