If one has been using carburetor heat during the approach, especially without a mixture change, one may have significantly enriched the mixture. With 100LL fuel, which contrary to the name does contain a high concentration of tetraethyl lead, spark plug fouling is a distinct possibility. If one has flown a prolonged descent with carburetor heat and no leaning, one may push the power up and find a rough engine that can't be cleared with additional carburetor heat...because the spark plugs are fouled.
I read this with some interest.
The R22 helicopter has a PA28-style 180hp Lycoming engine (though it's derated) and burns 100LL. I was taught (in the UK, so seldom hot or high) to use Full Rich mixture all the time, and always use full Carb Heat for descents. Unlike Fixed-Wing, every Rotary descent to land ends with something like a 'go-around' because you need nearly maximum power just to hover.
Landing an R22 requires serious attention to several details, but I have never been warned about this one. I am very low hours rotary, so I will ask next time I see my old instructor. Though if anyone here wants to chip in...?