I always found this subject difficult: right in between entertaining and worring.
On one hand it keeps your mind busy and it can give you some compensation in terms of personal satisfaction and some money reward. On the other it will show the whole world you are an absolute "L" that doesn't have anything better to do than working on private time.
And then again I wonder: where is all of this people that has fantastic things to do off working hours? Is it me or this is again a myth?