To begin with, how you spend your money is 100% up to you. On the other hand, I also understand why one doesn't want to upset or annoy their CA.
Before my CA quit LV, I tried to give her all the sales possible. However, there were also plenty of times when I ended up purchasing on LVdotcom because the things I wanted were restocked and I haven't had much luck trying to get them in store. My CA was genuinely happy for me every time I managed to get my hands on the items that I've been wanting, through her or otherwise.
One of the last things that I attempted to purchase from my CA was the Rouge Empreinte TP 26. She had one in store on the day they received a delivery but the sewing didn't meet my standards. I didn't buy it but still had her kept an eye out for another delivery. They never received another after the one that I rejected. Somehow I saw it being restocked on LVdotcom and I jumped on it. Subsequent to that, the item was discontinued. Had I felt guilty and didn't pull the trigger, I wouldn't have been able to buy it at all. I've been Googling every now and then but I haven't seen anyone selling it secondhand.
On the matter of buying preloved, she knew where I stand i.e. I'm very iffy about the origin and prior use or care of preloved items therefore I personally would not go there unless I really have to. The one item that I want and must get preloved, when the time comes, is the Empreinte Mazarine as it has been discontinued. My former CA knew about this and was super supportive. We've also discussed about my wanting to branch out to Hermes and even then, we'd both get giddy talking bags despite her knowing that clearly it's not her commission.
I've worn items that I didn't purchase through my CA to the store when I paid her a visit, on more than one occasion. We'd always talk about the items and she was always very keen on checking them out. We used to gush together all the time.
At the end of the day, I guess it depends on your CA's personality. Is your CA the understanding and supportive type or the opposite? With LV being so highly sought after and things are constantly sold out and/or not restocked, the CA should understand that this is business and nothing personal. And when the star aligns, you'd definitely give your CA the sales.
Nothing wrong with a white lie but you can also choose not to wear an item to the store. Do what makes you comfortable