Check service technician accreditations, experience with various fibers and tile types
https://extra-wiki.win/index.php/Tile_and_Carpet_Cleaning_Services_Checklist:_From_Grout_Cleaning_to_Deep_Steam_in_St_George_21360
Inspect technician accreditations, experience with different fibers and tile types, and training on stain elimination and grout sealing.