I am not sure how to tackle this one - Eddie is starting to pull the hair from the tip of his tail and eat it.  He did it this evening as we settled down to watch tv.  I know I should distract him - but I don't want him to learn that if he does this I will then give him attention!  He has already learnt that if he rucks up the mat and chews it I will turn around and look at him.  He has now just started doing it again. So now I have to leave the computer and go and do something else!   Earlier I removed him from the room so I couldn't see him.  I have to ignore it but stop the habit.  Any ideas? 

quick spray of the end of his tail with 'bitter apple' sometime after tea if its evening when he usually does it ?

I'd say distract - it's not a reward as such.
What he is finding rewarding is eating his tail.... so he needs some encouragement to do something else instead that is equally rewarding.... directing onto a satisfying chew toy or even a stuffed kong.

Check his anal glands.  This tends to happen further down towards the base but some dogs will chew at their tails and pull hair out if the glands are getting full and uncomfortable.  My old mongrel came to me with a big bald patch about a third of the way along, red raw and bleeding from her bothering it because her glands were so full.

Yes my dog also used to pull hair out from his tail and also nibble his back feet when his glands were full.

Ah!  Now that is something I haven't thought of - I did see him scoot the other day - just once and then forgot about it.  I thought feeding raw was supposed to reduce the chance of problems with anal glands!  

I raw feed and have never had any anal gland problems with my previous dogs but my latest youngster does appear to have glands that fill up. He also scoots occasionally and emits a fishy odour. I have had the vet take a look and although they didn't need emptying on that occasion, it appears that his glands are in a different position than normal so therefore they don't empty as efficiently as they should, nothing to do with diet.

My boy chases his tail when he has uncomfortable glands and also chews at his lower back. I always know the signs as they come with the smell. I have changed his diet slightly to try and relieve it but will always have to keep a close eye. 

It depends on the dog - some are just prone to problems and as hairypooch has found, the body shape of some means their glands might not empty properly whatever you feed them.  I have a couple like this - Linc in particular I have to empty every month or so, he has a sticky-outy bum and his glands empty mostly but not entirely, so fill up slowly.  Tends to be one side that doesn't empty as well.  He gets plenty of bones which keep everyone else sorted.  Paige is similar, same shape although she needs emptying less often.