Recently I was reading a grant proposal that a client had submitted for review. One of the sections on impact requested comments on client satisfaction, and it was essentially blank. Just a general statement that said "Our clients have indicated they like our services".
I thought the client didn't understand why the section was included, so I asked her to include results of client surveys, or even quotes from clients (appropriately stripped of personal identification, of course). Turns out she didn't have any.
It wasn't that no one liked the services. She said someone was always calling and sharing a story of how the charity had helped them. She (or her staff) just never actually recorded any of that. They got the occasional postcard or note, but just posted them on a bulletin board in the office for a while and then threw them away. They were positive reinforcement for the staff and that's pretty much where it stopped.
We were able to fill out the section just using what she could remember from a few recent instances, but if she receives a site visit, backing that up might be a problem. This is one of the ways that a nonprofit is just like any other business. Donors and clients both want to know that you can deliver on your mission. If you were a restaurant, would you throw away favorable recommendations? Growing and proving your nonprofit's impact is no different from capturing new customers.
Admittedly, this client is new at being a nonprofit, having been in business just over a year. I advised her to keep a record of those calls, with the date, the program it relates to if there are several, and a general description of the client, such as "29-year-old single mother of two children under five reported that she was able to obtain a job using our interviewing training". And of course, create a file and scan any written feedback to save it for eternity, as well as saving the actual document. When possible, have the client complete a short survey ranking your core services say from one to five, and provide a comment section.
Supporters want to know that you will make a difference with their money. It's about proving that you do make a positive difference, i.e. you have impact on the problem you are addressing. In addition, you can use the comments internally to refine or improve your services as well.