They suck back the crud from the RDA back into your squonk bottle and ruins the flavor.
as apposed to tanks where the crud is sitting in the tank

I've never noticed this in all my years of vaping
Sorry! I read your post earlier really quickly I read it incorrectly. So, what are the downsides to squonking? Can you recommend a basic set up?
squonking obviously isn't for everyone...to each their own.... not really any downsides (other than price tags, especially for me because I need dual battery mods) but it is a learning curve and even to date I am notorious for over squonking and flooding my atty and juice running down the side of my mod
the only downside I guess is finding an atty that works for you, but the same can be said with any set up....
I tried tank after tank after tank when I first started and just had no luck, either leaking or no flavor....dripping was the way for me....granted tanks have come a long way then what they were but still same issues if it's not leaking, there's condensation between the atty and the mod and flavor is diluted.
It wasn't until I got the profile rda that I finally found what works for me
though my set up is not traditional at all but it's what works for me
aegis legend with cthulhu squonk genius adapter and profile rda with mesh strip
I've bought several squonk mods since then but still prefer my setup...it's hard to beat the waterproof/shockproof/dustproof of the aegis and the 7ml of the cthulhu