Does infrared not look past bugs or dirt like they said?
No, that's not true in general, bugs show up on infrared all the time.
Here's a 12-second video which shows at least 3 different bugs showing up clearly on infrared, some very close to the camera and some further away:
Here's another one:
Another spider:
Even a mere spider web can show up on infrared:
Spiders building web on infrared:
Spider fight in infrared:
Those spiders have a more solid IR signature than the object in the video, but that might merely be the difference between a live spider and a mostly empty spider skin. Or it might be the difference between a camera with short focal length trying to look at close objects, and a camera with longer focal length for which close-up objects can be partially (but not fully) transparent
So clearly bugs can show up on infrared. What that guy actually seemed to be saying was that the focal length on this particular infrared camera was such that something very very close to the lens would not show up. But that's a claim that isn't very meaningful without specifics. How far away does an object have to be before it will show up? One inch, or one foot, or ten feet? Perhaps a dead spider or spider skin stuck to the lens would not show up on that particular camera, but would a dead spider hanging 8" in front of the lens show up?
Without that sort of clear specificity, the mere statement by someone on social media isn't very helpful.
So its your word versus his? What are your credentials again?
Have you operated said equipment. Because if he has, and you havent. Then I have to lean towards credibility here
Well, when it comes to the study of optics I have quite strong credentials, but that's irrelevant because I haven't asked you to rely on "my word" for anything. Every assertion I've made, I've backed with explicit evidence.