The easiest way to see is to closely examine around the water pump gasket areas. Your best bet is to do this from the pass. side as the driver's side is quite crowed. Look for extra amounts of Permatex that has ooozed out from the surface where the pump meets the block. Most mechanics are extra careful as a leak upon re-assembly is a no no. Better to overcoat the gaskets than to under-coat.
Also, If you look at the heads of the waterpump bolts you should easily be able to tell if someone has been wrenching on them. I only use air when I do those bolts (they are quite long) and it's a biyatch to get at them depending upon the degree of disassembly of other accessories surrounding the area. In other words, if the pump has been removed, you should be able to see that the evidence of that process.
To really see if the opti has been replaced? Well, pull the pump, then you'll know. Again, a quick examination under a lot of light will tell you if it's been removed. The timing bolt/opti bolts are very fine and bruise easiliy (scratch, etc) Hope this helps.