The only times I make an issue is if I think the hotel is trying to play games with me or lying to me. If I'm by myself, I really don't worry about whether I'm in a king or 2-doubles. If the hotel has a far more of one over the other and would like to give me 2-doubles instead of a king. No big deal.

But if I'm travelling with my wife, we prefer a king bed and I will expect the hotel to provide it. If they try to "upgrade" me to a 2-double room, I'll kindly ask for the stated preference in my reservation. Or if like last weekend, I was traveling with my son and asked for 2 doubles. The hotel "upgraded" me to a king on the CL. I thanked them, but asked them for a room with 2 doubles as I requested in the reservation. They did not have one on the CL unfortunately, and thus I was moved to a different floor. But again, I understood and didn't make any issues of it.

So basically, if the bed preference is in your reservation and you do want one or the other, then ask for it or invoke the guarantee (the hotels choice as to which option they prefer.)