Do demo account contests do good or harm for forex traders?

As it was informed by "Market Leader (US)"

Do demo account contests do good or harm for forex traders?

News of forex broker rating. The opportunity to receive money on a deposit by taking part in broker or DC forex demo account contests attracts many beginning traders. What do such contests give to a trader, how real are their chances of winning, and what are the brokers’ targets when arranging such contests? For it is widely known that
1. Demo account contests are a part of broker company public move in media.
2. Many traders fear that the winners of contests with a large prize fund are often... known in advance.