Alignments is a Revit plugin that highlights all line based elements in the current Revit view that do not align with any Grids in the project. The tool can detect even walls that are not aligned with a precision of 0.000000001 mm.
Use the demo file (House 1.rvt) to try Alignments.
Open the Floor Plan view "Level 0_Alignments". Go now to Toolbox -> Utilities -> Alignments. The addin will create a filter to highlight the walls that are not aligned with the grids in the project.
Alignments also works in other type of views. For example, open the 3D View "6. Alignments", click on Alignments (if you had not done before) and you will see the same filter in the walls are not aligned with the grid.
After creating the filter that highlights the misalignments you can keep or remove it. To delete the filter go to Toolbox -> Utilities -> Alignments -> Clear.
You can directly also isolate these elements with Alignments. To do it go to Toolbox -> Utilities -> Alignments -> Isolate.