I'm building with a lot of yellow, and there's DEFINITELY a difference in shades, yet Bricklink makes no distinction, so I can never predict which yellow I will get from a new seller. I only buy "New" bricks as well, so I don't know whats happening but I guess some sellers have old stocks of technically new lego Also, I bought a batch of yellow 1x3 tiles, and half of them already have hairline cracks from normal use. But they are LEGO brand pieces for sure, and this makes me sad. Happens with other tiles as well. Still, I'd rather have cracking pieces than no 1x3 tiles at all! I know the plastic isn't indestructible, but still, a 50% failure rate like that is kind of unacceptable, especially when the pieces are $0.10+ per piece due to rarity. That adds up for big projects.