This problem result is a Cloud/Mesh that has the basic correct shape but has bumps that are not part of the true surface. These bumps are often regularly spaced. This is due to small mismatches and it happens more as the surface becomes less textured and/or as the orientation degrades (esp. for low base-to-height ratio pairs). The bumpiness also tends to get worse as the sampling rate gets smaller. Try for a less dense result (i.e. larger sampling rate for the Paired Photos method, higher surface density setting for MVS) to see if you can balance the density required with the bumpiness of the result.
Alternatively for the Paired Photos method pick photo pairs with larger base-to-height ratios and/or decrease the project’s maximum residual and reprocess. And for MVS, increase the ‘Min visible images’ setting to limit weak feature matches.