You're not alone, I don't see any significant difference in the flavor of products (breads and pizza crust) when made with either compressed or IDY. Compressed yeast has three recognized aromas 1) Kind of a musty, old, damp newspaper like aroma. This is the normal aroma for compressed yeast and it is indicative of good quality yeast. 2) Compressed yeast can also have an ammonia smell to it. This is also a normal aroma as the ammonia is simply left over from the culturing process. 3) Then there is a somewhat sharp, offensive odor which is common to yeast that is beginning to die-off. In addition to aroma, look at the color of the yeast, it should be a light tan/buff in color with some streaking, but if the yeast is turning a dark color (muddy gray to brown) this is an indication that the yeast is getting too long in the tooth. Because compressed yeast is highly perishable, and as it dies off, it releases glutathione (an amino acid contained within the yeast cell) which actually enhances dough mixing, in many home baking situations it may appear to actually perform better. This is NOT the case in a bakery or retail setting though. Glutathione is a dough relaxer (commercially sold as "dead yeast") and as such, it works exactly the same as L-cysteine aka PZ-44 giving a softer, more extensible dough with somewhat improved expansion properties during baking which often result in a drier crumb structure, and a crispier outer crust, which can also be said to give improved flavor to the baked product.
Tom Lehmann/The Dough Doctor