Tar should not be tasted. Historical descriptions may call tar bitter, smoky, resinous, acrid, or medicinal, but tasting tar is unsafe and unnecessary.
This is a curiosity question, not an experiment. Tar should not be tasted. Different tars can contain irritating, harmful, or poorly identified compounds, and a modern person has no reason to put tar in their mouth to understand it.
Historical writing sometimes describes tar, tar water, tar preparations, or tar-related remedies in terms of bitterness, smokiness, resin, pitch, or sharp medicinal flavour. Those descriptions belong to their period. They are not recommendations and should not be copied as health advice.
The taste would also depend on the material. Pine tar, birch tar, coal tar, bitumen, and modern roofing products are different substances. Some may smell almost woody or smoky, while others are industrial and unpleasant. Smell is already enough evidence that taste is a bad idea.
The useful answer is that tar has been described as bitter, smoky, acrid, and resinous in historical contexts. The modern advice is simple: do not taste tar.