What is wrong with red lights? Genuine question
Red lights are harmful to reptiles because they disrupt their natural day-night cycles, cause chronic stress, and can damage their vision and "third eye" (parietal eye). People used to use them under the false assumption that reptiles could not see red, believing it provides a perfect way to add nighttime heat without keeping the animals awake. They CAN see it though. I mean, imagine if you had a red light in every room of your house you could NEVER turn off. I wouldn't like it. And it sure isn't natural, giving any benefit that uvb would. Deep heat projectors are my preference, other people use ceramic heaters. NEVER use electric heat rocks, they burn reptiles and have resulted in many reptile injuries and deaths.
When I see them in posts, I try to make my first assumption be that they don't know better and I might be the reptile's only chance at the person changing their practices- and that WILL NOT HAPPEN if I shame or embarrass them. The first attempt should be kindness, informative, and empathy. Most people genuinely do want the best for their pet, and you don't know if a relative, old book, or careless petstore employee gave them bad info.
Other people are more problematic, and have been doing it for years thinking 'it's worked this long, why should I change?" That's stubborn ignorance in action. Just because they don't feel miserable due to improper husbandry of the animal's enclosure (they're not living in it!) doesn't mean the animal isn't suffering. I most likely won't be able to help their animals, but I will chime in when I see them misleading others. It's pretty easy to fact check, and encourage everyone to do their own research and not just take someone else's word for it- even mine.