What advantages are there to painting the inside of the block?

See a lot of painted blocks that are rattled canned inside what looks like red oxide. Some are hemi orange. That **** don't stick on the outside how would it stick on the inside.

We do what the customer wants . Never seen an issue on race engines that come back for refreshing between seasons. But its like anything you coat. Some assholes just don't understand the definition of clean or proper prep.