Charities that call begging for donations often spend 50% or more of every donation on fund raising costs. For charities with "police" "sherrif" "fire department" or similar in their names the numbers are much worse. Often they give 95% of donations to the company making the calls.
If you want to give money to the police google your local police department and mail them a check. Do not give money to anyone who calls you on the telephone.
Charities, farmed out or otherwise, Dept collectors and politicians are exempt from the Do Not Call list. Maybe a few other things too. So pretty much like locks for honest people the DNC list is more worthless than useful.
Some places like the FOP farm out their charity requests. The only problem with that is the organization doing the calls takes a big chunk of your donation and the actual charity gets very little. I've gotten calls like this before asking you to buy a ticket for a child to see the circus or something else.
Since caller ID has come out, best thing since sliced bread by the way...I don't answer calls to numbers I don't recognize. If you have to answer the phone just say; "Not at this time, thank you." and hang up. No reason to get spastic, nasty or rude. I used to say that I just didn't make donations over the phone and they could send me something - they'd say it wasn't cost effective. I basically said - Sorry for your loss, and hung up.