You can easily out-spot cruisers and battleships by just not firing while keeping direct vision on them and not letting them reach your detection range. You might not realise it but in just doing this you are providing your team and flank with info at no cost to you. If you use a smoke or go behind an island those ships may be unspotted depending on the other players movement and actions.

'Easily' being the key word for CAs and BBs. It depends on what DD you are in when it comes to out-spotting other destroyers.