So here's the full story. I actually had BOUGHT this D50 this morning, a week after trying it (see my previous post). After discovering the cracks, sending pics to my luthier and reading your comments, I returned the guitar to the seller and got my money back. Pfiou! Can you believe that I have been a professional guitarist for 20 years and I didn't notice these cracks on the top?!? WTH!?! Must have been the light at the guy's place, as well as my the fact that I was wallowing in the sound of the instrument instead of carefully inspecting it. When I tried the guitar a week ago, he was showing me all the luthier's bills (very well known luthier in these parts, trustworthy guy) and saying how well maintained the guitar was, I kinda took that at face value.
One one hand, the seller was gracious enough to give me my scratch back, but on the other hand, he specified in his ad that the guitar had NO CRACKS. We even had a little argument as to what constitutes a crack, if you can believe it! When I returned the guitar, he was arguing that he didn't feel he had to mention it because they weren't really cracks, or that they were stable and didn't affect the instrument, that there was nothing to worry about... seemed like a real nice guy, I swear!
Anyhow, I'm relieved but at the same time very disappointed. Hopefully there's a decent D50 out there for me.
Also, I want to thank you all for your advice and comments. I am very grateful.