Reasonable on some guns, like a Theoben breakbarrel where incorrect assembly can cause the cocking arms to dig into the action, as they're held in place by the stock.
A poorly maintained rifle may have water damage underneath, and a silencer may be hiding a nasty barrel chop. However, if the potential buyer is expecting perfection and theres a bit of damage there then it may be just a pathway to hassle. On a springer, taking it out the stock can mean zero shift and other such problems, so it could screw up other possible sales leads.
At the end of the day, if you think it's too much hassle you can always ignore them and pass up a potential sale. with them.
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