It is only the exceedingly rare caller soliciting for a charity that can be considered legit if you define legit as meaning the majority of your donation actually funds the cause rather than paying the caller's salary. Most of the time less than 5% of the funds collected actually goes to the cause, the rest goes to "fundraising costs" including the salary of the caller.
Fundraising...one of the legit reasons to convince the one being called is spied for a reason. Do not engage. You are funding your own risks that your fund is called a "donation"