Do I have to clean/wash reclaimed brick..?

Question:before constructing a garden wall from it (not just stacking the bricks, but properly, with mortar) - I am not too concerned about the looks, but what about the construction - is it ok to re-use it dirty or do I have to wash the bricks or treat them with acid?
Don't really fancy the wall coming down after a while..

Answers:
All you need to do is remove all the old mortar. Nothing else.