When asking a product manufacturer/seller if a product will work for your hair(if they're responsive to customer inquiries), don't ask about what hair types, in terms of curl pattern and the tightness or looseness of your hair, the products work for. Ask about whether it works for low, normal or high porosity hair. Ask if it will work for fine, medium, or thick-textured hair. Ask about the potential outcomes you could experience based upon the condition of your hair.
For example, if you have highly porous hair(which is much more fragile with open/roughened cuticles), will Product A work with or against you? Will it calm frizz that comes with high porosity hair? Will it help keep the hair moisturized and help the ability to retain moisture? Or, will Product A just exasperate the problem? You're entitled to an honest answer and hopefully a recommendation for a better suited product that they [may] offer.
Asking if it works for 3c, 4a or Zz will not tell you whether it will work for you, because two identical heads of hair(in terms of curl pattern) can have totally different needs and can experience different outcomes with the same product(s).