I'm completely fine with the INT check in cases of physical inspection, variable DC or not, that makes sense. Extending things to add the Deception check is a little less clear, from a RAW perspective at least, and that was what i was curious ro get opinions on. If the character with expertise, for example, gets to roll deception (with advantage!) it puts the whole endeavor at a very different level of effectiveness. Assuming you can avoid the physical inspection pitfall.
[5E] Disguise Self - Scope and RAW
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