Dendrobium with faded spots and splotches on leaves

[Orchidreamer]

A plant doesn't need to have direct sun on the leaves in order to suffer from sunburn. It can also suffer "heat burn"--once I ordered an orchid online and apparently somewhere along its transit, it got cooked. The leaves exhibited blemishes very similar to sunburn.

Leaf mottling may be caused by nutritional issues, or possibly viruses, but you can't be sure until you do a virus test. You could grow it and keep it isolated just in case. It still looks like a nice plant!