The only wood floor sample I can't scratch easily is...
... a Lumber Liquidators brazilian teak sample with 'durafinish' on the back label.
I've collected a ton of samples of various woods now, and several more are wending their way through the postal system. We hope to decide in about a week what to go with.
In considering the Janka hardness scale, and looking at various options (we'd like a handscraped 5" chocolate ideally, with not a ton of grain, but we're very hard on our floors and want something we don't have to baby).
All the aluminum-oxide coated maple and walnut samples I've seen I can carve deep dents into easily with a fingernail. I will try to check the handstained walnut sample I have to see if it does the same. (From the Janka scale, it should ... unless it is the aluminum oxide coating that is really the thing that scratches easily.)
After the scratch test one of the samples I've ordered is an engineered Jatoba ... it is prefinished of course, but I'm curious to see if it is scratchable or not. If we were able to get the handscraped chocolate look that we want (that my husband wants most), maybe after all this an engineered wouldn't be so bad to consider.