but for shure some things are technically pure nonesense / damaging / life endangering:
1. stainless steel exhausts: obtainable at every corner, they crack after some miles and are hardly repairable. they will crack again and again. frustrating money-waste.
2. steering / brakes / wheels : its forbidden by law in germany to use parts (e.g. bolts) made of stainless steel on vehicles, as shear forces can damage stainless steel stuff much easier and can lead to serious accidents. i do not understand why reputable dealers sell that stuff. incredible.
3.nuts and bolts for the bodywork are also questionable, as the oxidation process won´t be on your screws or bolts and nuts, but on your expensive bodywork the corrosion progresses...

stainless steel is ok for some nuts or if you think you can "customize" your scooter with floor runners or a rear carrier that doesn´t rust so fast.