Dimming LED lights Bad?

[comtn4x4]

I have a set of LED fog light cubes I need to replace. In the process of looking for LED's which won't be overly bright I mentioned to a large well known LED company that if the lights weren't SAE/DOT approved I could dim them with my SPod. They said that would damage/shorten the life of the light. Is that correct?

Thanks in advance

 

[fourwd1]

this is kind of off topic, so that's where it's going.