All of the following guidelines are true for all waxing EXCEPT:

The guideline regarding checking the temperature of the wax behind the client's ear is not universally applicable for all waxing procedures. While checking the temperature of wax is important to prevent burns and ensure client safety, the recommendation to test the wax in this manner may not be practical or necessary for all situations.

In contrast, checking the temperature of the wax on the inside of your wrist is a common practice; it provides a reliable method for assessing heat without putting the client at risk. Additionally, advising clients to avoid sun exposure after waxing is a crucial guideline aimed at preventing irritation and skin damage, as the skin is more sensitive following hair removal.

The advice against double-dipping a spatula is rooted in hygiene and preventing contamination, emphasizing the importance of safe practices in any waxing service. Consequently, while testing the temperature is essential, the prescribed method in this option does not represent a standard or necessary procedure for all waxing types.