So you ordered it thinking that they had made a mistake, and might follow it up with another. That you were quite happy to profit from.
When they did send you the lens you were expecting to get and you got what you were expecting, if not what you were hoping for, you sent them a less than straight forward e-mail asking for an explanation. When you were pretty sure you knew exactly what had happened, and it was what you were expecting anyway.
Then to top it all they didn't promptly reply to your smart e-mail!
So to reply to your thread subject line.
"Should I be annoyed with Adorama" Well I would say only if you really think they have fallen from a high standard you might reasonable expect.
"or is it my own dumb fault?" Well I would say only if you think its unreasonable to try to take advantage of what you think is a mistake. But hey you are proving a point. I'll let you figure out what point it is you are proving, as I see it.
Price and listing mistakes happen... Walmart recently had pricing issues and had to cancel thousands of orders. They made recompense by cancelling the orders and providing customers with a $10 credit to use online or in store.
In September United had a glitch and were selling airfares for a fraction of their cost. They elected to honor the sale of the tickets. http://www.nbcnews.com/travel/united-airlines-accidentally-offers-airfares-nothing-8C11139753
I am not going to apologize for seeing an opportunity which would by to my benefit and making a purchase with the understanding that it may or may not come to fruition.
Around 5.5 years ago (before I got the Canon XS) there was a price mistake by Sears on some crappy entry level Nikon telephoto lens. Rather than selling it for $160, they sold it for $16. I managed to get two and then I sold them which allowed me to get the later that year. Are you seriously suggesting that it is a moral obligation for someone who see's what is likely a pricing mistake for them to notify the company of the same?
I don't consider my relationship with retailers as adversarial... but rather mutualistic (http://en.wikipedia.org/wiki/Mutualism_(biology).
There will be times where I will wind up paying more than wholesale for certain items (SD Cards, flash diffusers, bags, etc.) and there are times where I would expect to pay less than wholesale (used/open box items, discontinued gear, or gear that is overstocked with inventory).
I understand and accept that this wasn't fraud on the part of Adorama (which is a fine company and I have dealt with for a few years and I haven't had any issue with until this matter), but having a photo multiple times on a listing may be a mistake... but it is a knowing mistake which was made in repetition.
Once would be an accident, twice would be a confirmation of the negligence, and a 3rd time would be fraud. And there wasn't a 3rd time, so I'm not accusing Adorama of that.
I suppose my annoyance is that someone would actually confuse the 50mm f/1.2L with a 50mm f/1.8 mkii. That... and it wasn't really that good of a deal... so I have gear at a price that I don't really want. So I have to figure that out.
Let me know if I neglected to address a point... and I'll be happy to respond.