Pipetting: do human experimenters need liquid class information?
In my experience it is very rare to see a protocol for humans that describes how to pipette a certain liquid, but I don't have as many years pipetting as others do.
In general, it is left to the experimenter to observe the behavior of the liquid and act accordingly. It is quite easy to determine when a liquid is leaking (e.g. ethanol) or when it is very viscous (e.g. glycerol), and determine that a change in technique is required. In this case, I would ask someone else in the lab how to deal with the situation. This is something that robots cannot do.
However, not everyone has expert help available, and although it is fairly obvious when a technique isn't working, often the solution is not intuitive. Additionally, the advice of others in the lab could be unhelpful or even inaccurate. For example, I was told to cut the tip off a pipette in order to pipette Tween-20 more easily, however in reading for this answer have discovered that this is not recommended at all! (See eppendorf FAQ linked below).
Therefore, I would say that, unless the liquid is to be pipetted in the same way as water, it is always useful to provide information for those who are not knowledgeable or do not have easy access to expert practitioners.
For some examples of the sorts of problems that experimenters come up against, and therefore which liquids especially could use instructions in protocols, see this set of FAQs from eppendorf on handling liquids.