Generally, there are two main types of copper pipes (reddish-brown metal):
1) Clean, unpainted copper pipes, without attachments and contaminants
2) Painted copper pipes, without attachments and contaminants
Clean, unpainted copper pipes fetches a higher price as compared to painted copper pipes. More effort and resources are required to handle painted copper pipes, thus the lower value.
Brass is commonly found in copper plumbing pipes, ensure that the copper is free from brass, iron, and other recycling contamination. As copper fetches a higher value as compared to brass, separate your copper pipings from your brass plumbing fittings, to get the most of your recyclables.