There are a number of ways to review the results of the camera calibration and check to see if the results are accurate.
Make note of the final error when calibration is complete (the size of the very last bar or the number on the bottom of the Total Error Dialog). A value less than 1.0 indicates a good calibration. A digital camera should have a final error under 0.7. Very good calibrations can have a Final Total Error smaller than 0.4. Note these depend on the input marking precision (Preferences - Processing and Cameras, Process page) and these values here assume the default values (0.1 pixels for sub-pixel marked points).
If you have a good calibration according to the error bars you might want to do some further checks on the quality of the calibration. The Project Status Report is a good way to check for reported problems and to review marking residuals. The largest Marking Residual should be 1.0 pixels or less.
Use the Marking Residual Display (see Visibility on Photos) to check for any systematic problems. Set the exaggeration until you can see all error vectors. The directions should look random. If they do not look random (all point in one direction or toward center, etc.), then something has gone wrong. A lens with very high lens distortion that PhotoModeler cannot compensate for may cause problems like this.
The Camera Viewer Dialog also shows some calibration quality values, including Overall Residual RMS (in pixels), Maximum Residual (in pixels) and Photo Coverage (%).