Pinks can be traded in the pre-market session be routing through ARCA. This is a relatively recent change, sometime within the last year. Before this change, the only OTC stocks that could be traded pre-market were OTCBB. Not all MMs are active in the pre market session, so bids and asks that are displayed on level 2 are not necessarily "active". Interactive Brokers lets you trade pinks premarket, not sure which other brokers do.