When hiring a professional photographer, it's more than just seeing pretty pictures. There's an art, a dance, seasoned knowledge that comes into play and I believe a photographer can make or break the guest's experience almost entirely on the use of the flash.
In a nutshell, the flash can really add to the quality of an image, but I still use it sparingly. In this next photographic example, each couple was lined-up for a posed photo before they entered the barrel room dinner. They expected me. They were smiling and ready. I used flash to give the image the best quality I could.
Once dinner began, there were boisterous toasts, throw your head back laughter and lean in close chats. The light was crazy low. Yet I turned off my flash. The importance of not disturbing any of the moments was great. I took over 100 images during dinner and if I had my flash on, I can only imagine what an annoyance I would have been. Instead, I pretty much blended into the evening and the guests barely gave me a glance.
I find this to be an important attribute when hiring a professional. There might be a few photographers who disagree with me and that's perfectly fine. What's important is that you find and hire someone that fits into your vision and fulfills the experience that you hope to have.