are SA's / boutiques okay with buying pre-loved?

I don't think they would mind. I mean at one point, it was brand new just like all our bags. And I would think that owning pre-loved is just as good for the business instead of not being able to buy anything LV at all.
 
I've shared my finds before. I think the beauty of a brand like LV also lies in its sustainable nature. The products last for ages, and I think they should be sold on if they can better be used elsewhere. It allows people like me to own multiple products and explore the brand without going into debt.

Plus, buying pre-loved is kind of comparable to buying in another store or country. From a sales perspective, it's either from your SA's store or it's not.