"When we associate with the virtuous, we form  ourselves in imitation of their virtues, or at least lose every day, something of our faults." Pope St. Agapetus

How true this is! Associate with virtous persons can have a positive impact on us. Associate ourselves with shady characters may encourage us to imitate their life style.  Or to put it in another way. If we work in a perfume factory, we will smell like perfume. If we work in a fertilizer plant, we will reek of the fertilizer smell. Choose the environment that will lead you to God. or the environment that will us away from the Lord. Companions who do not lead us to God are not true friends.