have i used my foot while loosening lug nuts on a car wheel? it's nearly impossible not to, but you have the whole weight of a car balancing it, that being said i doubt(maybe i'm wrong) that most car service manuals would tell you to stand on the wrench. it's a poorly designed tool, someone pointed out to the manufacturer that it lacked leverage and rather than improve the design they said, "you get leverage by standing on it, duh" poor design,

i just checked out their website and there are lots of generic rebranded accessories and a few pretty things, sometimes when designing something, especially a tool, pretty isn't enough