If I'm not completely mistaken, Izhmash, the factory that makes Saigas also makes the AKs issued to the Russian troops. Of course there are some differences between the full-auto AKs and semi-auto Saigas (mainly the trigger assembly and selector), but the basic components should be the same so they should also be equally reliable.
If you're shooting surplus ammo, the gun will definetely get dirty fast but it will still keep on running. It is advisable to clean the gun every time you've shot corrosive surplus ammo, but I've sometimes left my Saiga sitting dirty in the safe for couple of weeks before cleaning it. The barrel and chamber are chrome lined and I haven't seen any rust on them. The threads of the muzzle brake can get a bit sticky but are easily cleaned. Once had a little rust on the bolt face but it cleaned out nicely with a little CLP and a bronze brush.
Just run more ammo through the gun, it'll be fine