This post has been migrated to http://www.thinkcode.se/blog/2015/07/17/tell-dont-ask
Objects that expose wrong information are complicated to work with. They force you to dig for the information you really need. It is easy to create a model where the users are expected to know a lot about the domain and therefore force them to dig deep into an object structure to get the information they currently need. This can be avoided if you strive for telling objects what to do and only ask them occasionally.