Any 14900 Omega Constellation case needs careful scrutiny because it is one of the most ubiquitous of the faked dog-leg lugged cases around. There was a bit of a lull on eBay for a while but I notice them creeping back from time to time, and It's hard to say if another batch has been shipped from the Orient or it's just the earlier ones being recycled. Never-the-less, extreme care should be exercised.
The latest fake to surface is shown in the capture of this current eBay listing. The seller watches-n-such is also selling an appalling "homage" to a black Constellation pie pan dial, probably from the same source. In this instance, the "n-such" being sold as NOS may come back to bite watches-n-such in the posterior.
While Constellations are not the most faked vintage pieces by a long shot (Rolex models from the 60s and 70s have that dubious honour), cases 14000, 14902, 167.005 and 168.005 in stainless steel have been targeted over time.
If you're not aware of the checks to make when assessing one of the above models for purchase, please review this essay.