Garaghak's Sewer vs Rotten Flesh

How close are they?

ΔE 20.8, loose: different enough that you should pick on purpose. Rotten Flesh is noticeably darker, more muted, warmer than Garaghak's Sewer.

Can I use Rotten Flesh instead of Garaghak's Sewer?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Rotten Flesh is noticeably darker, more muted, warmer than Garaghak's Sewer.

Can I use Garaghak's Sewer instead of Rotten Flesh?

The same difference applies the other way round: Garaghak's Sewer is noticeably lighter, more saturated, cooler.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.