I'm not sure, but I think I may have reached a new level of laziness in my kegging practices. Last night I needed to clean some kegs so I devised a way to hook the liquid out post up to my kitchen tap. I put a vent on the gas post and ran hot water into the keg while shaking it and tipping it upside down. I kept this up until the water ran clear from the keg. I did open a couple after this process to ensure they were clean and slime-free. I made up 5 gallons of Star San solution in one keg and used CO2 to push it to another keg. I repeated the process and ended up with two cleaned, sanitized, and CO2 purged kegs and one clean keg full of Star San. I'm not sure of my time on this but it sure seemed quicker than my usual process of opening them up and rinsing them out, disassembly, and sanitizing and purging.
I'm not seeing a risk since the kegs were all sanitary to begin with. Maybe a chance for some off flavors from decomposed yeast if they're not sufficiently rinsed out? Anybody have experience doing something similar and care to share?