Under certain circumstances, I'll endorse the purchase of an outerwear garment made out of synthetic materials. My rule of thumb is that one must restrict oneself to plastic vests rather than jackets (less surface area to snag or ignite in flames). If I'm going to make the purchase, I'll use the following synthetics selection criteria: item must be filled with real goose down (Western Mountaineering), item must make use of mile high, 100% polyester shag pile (Patagonia Retro X vest), or item must be made in the UK, be labeled a "waistcoat" and come with cartridge pockets (bonus: contrasting suede patches on the shoulders).
Here's a photo showing a plastic vest (an old Barbour Keeperwear vest) in its proper context.
