I've only played with one 1ZZ-FE that was a known oil burner, and a few more that were not - most of the oil burners involved a bunch of non-Toyota imports and mainly domestic ones (one Ford Taurus 3.0L V-6, older Quad-4 motors, Saturn 1.9L SOHC/DOHC, GM V-6, GM V-8, older carburated SB/BB GM and Mopar SB/BB/Slant6 engines, BMW, DSM, and Hondas).
That 1ZZ-FE for the most part - looked like it was in good shape, aside from consuming an excessive amount of oil (1 quart @ 150 miles). It didn't have any outward signs of being a oil burner - sludge, obviously scored or out of round cylinder walls (polished smooth), hard carbon deposits, etc. Some residue on the bumper, but it didn't smoke at all from the exhaust. Topend of the engine looked good - nice golden color, no heavy deposits, no big chunks or patches of sludge anywhere. It actually looked cleaner than my own engine (my pics on photobucket site in my sig - but that was probably all the additives this guy was adding to the oil to clean up the engine.
Looking at the piston, fair amount of carbon deposits (typical for an oil burner), rings did look good, though some were broken (oil ring side rails), which surprised me. Oil control ring (expander ring) looked OK, was still loose and was pretty flimsy - but not sure if they all are like that. Rings were not stuck, some deposits in the ring lands, but nothing that looked like it would compromise the specs. Before the engine got torn down - compression test showed it was still good 185PSI+ each cylinder. Plugs were toast after 6 or 7 months - about 5K-8K miles tops before they were completely clogged with ash and oil fouled.
Unfortunately, didn't take any pics - as there the engine cleaned prior to it being pulled down. You name it - it probably was run through the engine. AutoRx, Seafoam, MMO, Rislone, Gunk, BG products, Rotella, ATF, diesel, etc. So the real culprit probably got "washed" away. Be nice to get a hold of an engine that is consuming an excessive amount of oil, but had nothing done to it other than topping off the oil level. Then on teardown - should be able to spot the problem.
Since many have reported a sudden switch to heavy oil consumption, especially when the mileage starts hitting 100K+, I'll just wait it out and see if it my car starts too. But since I used only synthetics and monitor my oil with UOAs, I'll probably be waiting for some time.
Yup, 5000 miles changes - and that was when they lowered it too - used to be longer. The book in my '96 Camry recommended 7500 mile intervals on conventional oil for normal driving conditions. We stuck with that interval and only recently dropped it to 5K on high mileage oil because of the miles on it (switched to 5K drain intervals when the car had 280K miles on it and started to use 1/2 quart of oil between the 7500 mile intervals). Now it drinks a few ounces between the 5K intervals, but has more than 300K miles on it.