Hi.
I need your help on this.
Could anyone notice anything unusual by looking at these pictures that I about to purchase via E-Bay? Any possibility it might be a fake or a Frankenstein Seamaster? If I purchase this and after receiving it, what things should I check first to make sure it is authentic? I will open up the case to see the movement.
Thank you in advance for your help.

 

just an old, worn SMP.

 

Genuine Omega, nice daily wearer. An ultrasonic cleaner and a satin buffing wheel will greatly improve the bracelet. Case should probably be left to a sympathetic watchmaker if you decide to have the movement serviced.

 

Thanks all. According to the bracelet, it should be 41mm large case right?

 

That is the 41mm case, yes. Model 2531.50, from later than 1997 as it has Superluminova lume. As noted above, that looks a bit well worn but a full service would bring it up as new, the case condition suggests that the movement probably needs servicing too. Ask for a close up pic of the back of the lugs, there should be a tiny 8 digit number lasered on there, if you post the first couple of digits we can give you an idea of year, if it is missing it may mean that it is a grey market watch which lowers the value a little and is a turn off to many buyers.

 

Today I received my watch and there are two BIG problems..
It was a bit dirty with black gunk and I was not able to remove spring bars, so I gently washed the watch with toothbrush and soap. Then I realize the back cover was not closed tightly(I was able to turn with my hand). I guess because of the gunk it was not closed all the way and as soon as I washed it, the cover got loosen? So, I dried quickly and opened the back cover to see inside and I didn't see any water damage..
Should I be concerned about this?
Also, I can't locate the serial number on any lugs. Can this be possibly a grey market? If it is grey market, by how % it lowers the value?
Thank you.

 

Have you not looked anywhere else on the Internet? It took me less than a minute of searching to find this and I don't know anything about SMPs:

http://forums.watchuseek.com/f20/serial-number-lug-missing-fake-146163.html

 

Is there a serial on the movement or has it been scratched off? You didn't post a movement pic so I can't tell. If the movement serial has been removed too then it is definitely less desirable and therefore of less value than otherwise. Hard to estimate but £100-200 less IMO. If it has been removed from both and not declared on the listing you have a fair case for a return, I have done exactly this myself.