Never used them , not even tear-offs now . I treat inside of lens with anti fog-and outside with rain-x. Was never able to pull just one tear -off-not worth it. IN US VMX we usually run five laps. If it is that horribly muddy, I make a decision to risk damaging rare parts or not. If the dirt is not sinking, I put around. If it is worse, I watch others break parts.
Worst crap stuff I used was a really cheap chain. I stretched it to where it flew off in moto one. I actually removed links for moto two and stretched again, not as much but too much. It sucks to spnd mega $, but a cheap chain...well I can't afford it. I now stick with DID, Regina, or CZ chain only.