I know the Type 59 has terrible spotting but I literally rammed an invisible Wespe, I mean, I rammed something, 3 seconds later aftr the Wespe rotated I spotted it. With a 100% crew you'd think i'd spot a tank right in front of me lol.
I heard that the Jagdpanzer 1 was the best at camo, TD, tier 2, small and with 100% camo and camo nets. I'm sure you'd need to be like 1m away from it to see it. Its a ninja tank.
Then fire the 105 (by necessity @ close range) and be spotted by everyone abd too slow to escape. You better hope its a 1 shot kill. Hetzer sucks even tho my best match was in it
There's also the possibility of how fast it was going. It's possible that it got inside 50 meter and left it before his spotting updated in time. It's certainly possible the game/server sync was slightly off and his speed was enough he probably never saw him as he passed him.
According to the WoT spotting spreadsheet (don't have the link on me, using the file I saved to my hard drive), best camouflage rating while standing still = SU-85B; while moving = T82.