We anchored in Martin Slough on the Columbia River one evening. We had the standard 15-18 kts NW wind that always blows in that part of the river that time of year. Set the hook well downwind of a 20-some foot Bayliner and started getting ready to make dinner. The 2 couples partying on the Bayliner light off their charcoal grill maybe using a bit more starter than necessary. About that time we noticed they were dragging our way with a 4 foot flame rising out of the BBQ. Sort of like an Erroll Flynn movie. I called to them that they were dragging, their first response was "No we're not, your are" They the did a double-triple take and did the right thing.
At my wife's insistence we now have a standard protocol when we get into a close anchorage. We pick a spot we think is OK then cruise near any boat that may feel impacted and tell them our plan and ask their opinion and ask them what they have out. Almost always the glare turns into a smile and a cooperative conversion the can produce an invitation to come over for a beverage. I could tell the story that lead to the development of this procedure but I hate to show myself in a bad light. ;o).