I guess I should say that this type of interaction with passers by and onlookers rarely upsets me. I tend to engage with the inquisitive - assuring them that yes, one can still by film for that. That there is actually a pretty good selection and all of what is available is excellent.....and so on.
The only time I get kind irked is when I have the camera set up on the tripod and, while waiting for the light to be right, somebody engages me with the usual barrage of questions and admonitions to "go digital". The light passes and I end up packing up and going home.
When I have the 4x5 set up, I'll let anybody who's even the slightest bit interested look at the ground glass & c.
Sometimes, a serious amateur or retired pro will come along and say something like, "hey, I used to have a Nikon F2 (or what ever) just like that one...." and we'll get to talking about cameras and trips and jobs and so on. This can be more satisfying than making photographs. Sometimes, I even ask them to sit/stand still for a portrait.
...and speaking of pros...I've met a few along the way...usually a wedding photographer, sometimes, I'll bump into a press photographer. These people are always interested, generous and patient.