If you set the ADI on the ground and in the hover you have pitch up or pitch down indication, then that angle is the angle of your undercarriage with refernce to the ground. This is important if you have to do a serious movement close to the ground such as a reject on take off.
Take the S76, it can have up to 8-10° nose up in the hover, if you then level the ADI, then put the nose down 5-10° for take-off you are in fact only levelling the aircraft and you are going to require a lot of runway for your take-off. Conversly, on landing the max nose up attitude close to the ground is 10°, rotate 10° nose up and you are at 15-20° with an expensive noise comming from the tail area.
In the cruise at whatever speed you fly using all instruments not just the ADI, it does not matter whether it indicates a nose up or nose down attitude, you fly using the information it gives you.
There is nothing magic about instrument flying, practice makes perfect, well almost!