Carbon On Valves?(Valvestem Seals)

[SnprSlick]

I just pulled my head to change out the valve stem seals because my compression was reading 180 across so I figured it wasn't the rings and my car was drinking about a quart of oil per week. Anyway, I pull the head and look at the valves. This is the first time I've ever pulled a head and I'm still learning. But there was a generous amount of carbon build up on the exhaust valves. 4 of the valves looked clean but the others were build up with carbon. Also, when pulling off the valve stem seals, the ones on the exhaust valves were easy to pull of by hand but the ones on the intake had to be removed with pliers. Is that a good indication that my valve stem seals were bad? Or should I still suspect rings as the culprit?

EDIT: Also some backstory:
I bought the car last October. The guy said the car had thrown the timing belt and he got the head rebuilt with new valves and everything. The valves weren't bent so I figured they probably were new valves and the clean ones look almost NEW.

 

[LiquidX]

Were the valve stem seals rock hard? 180 compression is pretty good to have and a leak down test would have proved better for this situation. IMO I believe it is bad seals.

 

[Hitmachine101]

im gonna have to agree with liquidx, 180 is basically new compression if i remember correctly, i think your looking at your rings in all honesty,

 

[SrKegler]

I'd bet they only replaced the bent valves when they did the head.

 

[bluegs03]

Yea if some of the valves look new then those were the bent ones and the others are the old ones left in there. I bet the old valves still have the old valvestem seals on there, that would be the first place I would check to find the oil burnage.