No do not worry about it. They dont really deal against you. They make there money from the spread so if they busted every new account they got they would go out of business. Us retail traders dont are so insignificant to most of the better companies they dont worry about us.
Uuuuhhhhh...... there are STP and ECN brokers operating in DD model and some rare Market Makers operating in NDD model. Dealing Desk is not Market Maker and Non Dealing Desk is not STP nor ECN. Dealing Desk is when trading is not automated, it goes through a dealing station where the dealer choses wich price is giving to you. In case of STP brokers they see the offers from its liquidity providers and chooses the one who can led them with better spread commissions. The reason why STP and ECN are sometimes mislead with NDD is because these times we are living the orders are so numerous that human intervencion is almost imposible and so they just made it automaticaly. Instead Market Makers are human manipulated and that is why most orders take a long time to be filled and that is why Market Makers are mislead as equaly to a DD.