It may be worth trying to get some reporting points set up, as I think that would make things clearer. Would also help noise abatement, as I have to confirm procedures with non-local pilots and that takes up valuable RT time. I'll follow it up with my boss.
I could ask them to report more information - in fact they normally give it anyway. This doesn't seem to solve the problem though as they don't report a geographical feature, only a bearing relative to the 'field (i.e. SW, N etc). Also, this doesn't affect the departure side of things...
We do have contact with the rotary operators, but I don't believe we've ever raised this point - it's one of those little things we all live with up to now. I'm new in the job and keen to give a good, safe service, which is why I'm asking the questions. I might post a similar query on the ATC forum to see if this is a local issue or one others have noticed too...