I know it can be tricky to tell whether a wardrobe is made from solid oak or just oak veneer, but there are a few tips that might help.
First, you can check the edges of the wardrobe doors and drawers. If they show grain patterns that match perfectly all around, it could be veneer. Solid wood generally has end grains that look different from the side grains. It might take a little practice, but once you know what to look for, you'll get better at spotting the differences.
Another way is to look at the weight and feel of the wardrobe. Solid oak is usually heavier and feels sturdier when you try to move it or when you knock on it lightly. Veneer, on the other hand, covers a lighter core material, so it often feels less substantial.
Finally, consider the price. Solid oak tends to be more expensive due to its durability and quality.
Of course, a clever and determined scammer can find ways to fake one or all three of these attributes. If you really want to be safe, it's best to buy oak wardrobes from reputable sellers who specialize in wood furniture. Like this one, for example.