Re: BullMerde
Same for me, an ex Genius. The interior cleanliness of the machines I repaired entirely depended on the environment they had been used in. The range was wide and we could and did refuse service on more than one machine including one that had some insects living inside it.
As for removing the glass to clean it - 2012+ iMacs have the glass bonded to the LCD to allow the machines to be thinner, so the whole assembly needs to be replaced.