no they dont!!!!
some are overdosed some are underdosed.
good companies use better oils and powders,others use whatever they can get.
example: british dragon makes test prop. some think its great some dont. the people that dont useally cant afford it cause they will find a ug lab that will sell it for 20 bucks.
or you test prop from Bulgaria which is good.alot of people dont want to spend the money on quality gear cause they can get ok gear for a cheaper price and just take more of it.