Covering your scent has been practiced by hunters for thousands of years. The practice isn't a gimmick. The difference today is that we can buy products instead of making our own like has been practiced as long as humans have hunted. Lots of ideas have been tried with varying degrees of success. Wind and game can come from 360 degrees and both can change unpredictably. Being upwind is great if possible, but it is rarely so.
Nothing is 100%, the best you can hope for is to limit the scent so that instead of smelling you 200 yards away an animal may only smell you within 20 yards. And it isn't always necessary. If you're hunting in many crowded areas or on farms etc. game animals smell and see humans constantly. Smelling or seeing a human doesn't always cause a deer or other game animal concern. In a remote wilderness setting it is more of a concern, especially when hunting with short range weapons such as archery or handguns.
I think that most of the clothing sold to trap scent has proven to be less than successful. Buying covering scent out of a bottle can be effective. Just remember it isn't 100% and you'll smell like deer pee, skunks or other wild animals. Only you can decide if it is worth it. I'm not so sure about the apple and other fruit scents. I guess in specific locations. I've taken hands full of leaves, dirt and other forest debris and rubbed it into as much of my clothing as possible in the past and it seems to help. If hunting on a farm with cattle stepping in some cow patties will help cover your scent and be a natural smell game is used to.
Preventing odors on your clothing is probably the best approach. Avoid eating or gassing up your truck wearing the clothes you'll hunt in. I've known guys who stored all their hunting clothes and gear in plastic garbage bags all season and not washing them till the end. Depending on the area some pine or other tree branches are stored inside for the scent. I've known guys to hang their clothes near a campfire for the smoke smell. Forest fires and smoke are not unusual and would not alarm deer. It is strong enough to cover human scent pretty well.