>"you can be confident that a monoclonal antibody contains only one antibody, that recognizes only one antigen"
Not sure if you really meant that since it is kind of contradicted by some later statements, but all antibodies are promiscuous. Thinking you can map one antibody to one epitope is extremely dangerous. It is a matter of quantity (affinity/avidity), not quality.
Exactly. When i did immunocytochemistry, i had more confidence in polyclonals than monoclonals. If you get a strong signal with a polyclonal, then you know that many different antibodies are all binding the same thing, so it's very likely it's your protein. If you get a strong signal with a monoclonal, that's just one antibody - so it might be your protein, or it might be some other protein that, by chance, your antibody happens to bind tightly.
Not sure if you really meant that since it is kind of contradicted by some later statements, but all antibodies are promiscuous. Thinking you can map one antibody to one epitope is extremely dangerous. It is a matter of quantity (affinity/avidity), not quality.