This is a difficult one. The question of status may be a factor. However, this would depend on your relationship with the staff. If you are, say, of similar age and have an open, friendly, ‘one of the team’ relationship with them, then it may not be too difficult.

The element of threat that would attend a less open relationship would not be present.

You could set aside a time each day to work on the counter in order really to get to know what life is like for them. Even if you have done their job, you may have forgotten what it is like! It may have changed since your day. Direct conversations about lead generation would probably not feature in your research times. However, you would need to have a period of reflection after each ‘research session’ to think about the implications for your research question of what you have just experienced.