every bottle is a new fermentation. so they are all different. some could have different amounts of sugar, oxygen, yeast, temperature, amounts of sanitizer and even chemicals in priming solution.
I've had batches where some bottles didn't carbonate and some over carbonated. this was probably due to incomplete mixing of the priming solution. I've had huge off flavors from chlorine in the priming solution because I didn't boil it long enough. there are a number of variables at work.
can you describe the off flavor? maybe we could help track down what went wrong.