In addition to VulpesRex. Because he nails it pretty much.
Consider lending a fursuit the same as lending a car.
I for instance do not trust people lightly with my stuff. However, I have 1 friend will lend my car anytime any day because I know him for so long and I know he has the same ethics I would want for someone that lends my stuff.
Most others I will flat out refuse even if the situation is 'dire'. I hope most people will relate that a car is easily damaged, is very expensive and hard to repair and replace and a lot of things that aren't even directly visible could get damaged because of a difference in customs or unknowingly because you do to know that car that well.
Depending on the suit they can be easily 2000+ euro up to 5000 euro. Which... makes it basically as expensive as a (cheap / second hand) car.
Mostly the same rules apply to, if you would damage the suit. A lot of things can NOT be easily repaired. Even if you would be able to find replacement parts, it would always be visible.
Their are 'wizards' out their that I know can do miracles with mere needle & treath, glue, a bit of nail poish. But fact is if you strive to be all you can be, it kind of stings to have a part that is not longer 'perfect'.
Bottom line (for me at least), asking is always fine. Be aware of these points and you might get no for an answer often.
Unless that person you ask is absolutely positive they trust you with, which is essentially a part of their being (I might even dare say, part of their soul) then I hope anyone that receives 'such honor' to take care with that responsibility.
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Take care, have fun, enjoy.