Tiles in wet applications should be slip-resistant and meet the minimum industry standards. Beware, however, not to choose tiles that are too abrasive as they will cause maintenance issues in that they’ll require more frequent cleaning and will be difficult to clean.
Tiles in high-traffic applications should be durable enough to withstand the amount of wear and tear they’ll be subjected to.
When in doubt ask the manufacturer to provide written verification that a particular tile will be suitable for its intended use. Perform quality assurance testing to verify the manufacturers’ claims. Also, have the client sign a disclaimer that they understand the limitations of the product they’ve selected.