Actually, I've been using a night security camera I have hanging around. You know the type, they have IR LEDs and thus they can see my IR diode's beam. I can't get an exact measurement, but a 25%, 50%, 75%, 100% type examination is quite possible and practical.
That's a bad type of measurement. Depending on the IR power of your device, the goggles have to attenuate the light to well below 0.1 mW to be called "save". Do if yo have a maximum power of 100mW IR light from your Laser, you need a 1:1000 filter for that wavelength, or in other words at least a "OD3". The "3" corresponds to "1:1000". An OD4 = 1: 10.000, an OD6 = 1: 1.000.000
So if you "guess" it filters 75% of the wavelength the camera is sensitive to, then you still get 25% of the power passing. In this case your Laser should not exceed measured(!) 0.5 mW
And then again, IF the goggles cut the power in the right amount, it has to swallow almost the entire energy of the beam to do so. For beams > 100mW the material must withstand long enough to protect you, before it eventually gets destroyed. For the wavelength in queston the glasses "look" like an ideal black burning target.
No problem for relatively low power, but the guy with the 40W handheld CO2 Laser must get a really sturdy pair of glasses.
I often find that if a seller is ignorant that does not make the product worse but I do share your concern.
I often find that something that is not explicitely grantet is something you should not expect - and even then. The seller has no specific topic on Laser and Laser safety. He sells what he is able to get cheap. I don't see a hint that he even has basic knowledge, what this is all about and probably is only listing "specs" that he got told from whoever sold him this before. Otherwise he would list the attenuation for specific wavelength. How else would you choose the right one? There is no "one size fits all".
These might be great. Or they might be complete crap. You just don't know. Do you bet your eyesight on them just to find out?
But it really depends on YOUR Laser. If you have a moderate green DPSS and want to be save from spilled IR of the pump diode, than almost any "block red" will do. You start with pretty low IR power and 808nm is just a bit off the deep red. If you search protection while adjusting a high power CO2 Laser, you should spend a few bucks for REAL goggles that can reliebly keep out wavelength >10.000nm which is a completely different kind of IR.
Don't judge the price for safety goggles on the price for the Laser. Judge them on the price for a new pair of Eyes.