Suppose an organization represents that its mission is cancer-related. You may be interested in aiding one of these causes more than another. Likewise, suppose you are solicited by a law enforcement association. Most of these organizations are labor associations, but some also donate money to local charitable causes. You should understand how your contribution will be used before you contribute.
Charities have local, regional, national or, even, international missions.
It may be significant to you to know where your dollars will be used. Some national organizations conduct programs in your local area, others do not. If a local presence is important to you, you need to find out what kind of local office or program the organization maintains. Paid professionals are required to disclose their status to potential contributors. You would be wise to ask for that information at the time you receive the solicitation.