On paper Communism is supposed to be about equality, the brother-hood of man, giving only according to your skill and ability and taking what you need, and so on, so it works on paper. Marx never factored in the reality of the human element. Lenin and other Communist leaders created a faulty quota system, whereby a factory generated a product without acknowledgement of differences in size, taste, color, and the different nuances that people want in a product. Shoe factories accomplished their quotas, without concern for size, color, style and shape of a shoe. 500,000 pairs were ordered and 500,000 were made, all the same size, color, and style. Nothing mattered but the quota. Wheat rotted in the fields because there was no incentive to harvest it. You worked and you were given a voucher to procure your needs; food, bread, shoes that didn't fit, etc. The lines were long, the product you wanted was not available and thus because of the flaws of Communism, a culture of corruption instituted itself. You could get what you wanted, but you had to go outside of the system to get it. An underground economy flourished, and you know, money talks. Whereas with the system you were lucky to get a television or radio, with a bribe, you could get a high quality American TV which was probably prohibited, but you could bribe the customs agent, then the police, which would almost certainly visit your home, to overlook your purchase, and so on. There really was/is no incentive to follow the rule of law in Communist countries. Thus, corruption on a mass scale.
Corruption happens when the foundation of the country is faulty. One cannot build on communism without corruption, as it's the major problem with communism: bureaucrats extend their fiefdoms, manage for their benefit and continued existence, hoard capital and refuse to take risk, and as a result there is little progress, no jobs, and stagnant wages in everywhere except the bureaucracy. The bureaucracy is then tasked with funding the Communist Party which proceeds to eat up any profit leftover. Ergo, everything built on this foundation is corrupt. It cannot be reformed, it must be razed and built anew, as Rome was after Nero's Conflagration.