Three actual applications of spray plume sensors for industrial coating operations are presented. Two of these are in the aeronautic industry and one in the automotive industry. Depending on the application, different types of sensors were used ranging from plume shape monitoring (particle trajectories) to full plume characterization including in-flight measurement of individual particle properties. In each case, the process monitoring scheme developed depended on the manufacturer's requirements as well as the nature of the information provided by the sensor. The significant differences in usage and working conditions compared to an R&D environment are examined. Advantages and drawbacks in each of the three situations are detailed. A tentative forecast of coming developments in this field is also given.