Fleece Vest = Outerwear
Anyway, my point, and I do have one, is this: IMHO, a fleece vest looks like outerwear. When wearing it, you project the appearance of wearing a coat. In fact, almost all polar fleece gives off the same vibe -- "I'm outdoors".
I allow there are exceptions, but in general I wouldn't wear it except for leisure activities. And never as shown, with a short sleeve t-shirt.
And, another thing. These kind of cotton t-shirt type turtlenecks are UNDERWEAR, especially when done in cutesy little prints. Together with a fleece vest, they could be a cute look for a sporting event or game night (WITH JEANS).
Just my opinion, but I thought you'd want to know.