eBay is definitely a gamble, whatever perspective you take, so I think you have to view the experience in balance. For me that means overall I'm up on the good experiences and nice surprises, allowing me to feel less disgruntled at the negative aspects. I think you have to use it regularly for the 'balance' to happen, you can get very badly burned by the occasional dabble otherwise.
i confess I don't use it so often nowadays, and have become shy as a consequence. I'm definitely tending more towards the idea of coin fairs when the money starts rolling in. When you know what you like, eBay can be a struggle.