They should all be vac sealed with a desiccant pack inside. It isn’t important to have every bit of air sucked out – that’s what the desiccant pack is for, to get any moisture from remaining air – but the bags should definitely be sealed.
But even if they are sealed and have a desiccant pack, it is no guarantee they have been that way their entire life. I’ve had rolls of Nylon, PETG, and PCTPE all arrive from Amazon perfectly vac sealed with desiccant packs – only to find the filament full of moisture (popping, steam, bubbles). I even got a replacement reel of PCTPE direct from the manufacturer that (despite arriving in a vac sealed bag, with desiccant) was full of moisture.
I gave up and bought a modified food dehydrator. I now bake every roll of filament as soon as it arrives, before placing in sealed containers with desiccant for storage. Obviously not every roll needs it, but many do – and I was tired of sending them back, hoping for a dry replacement that sometimes never came. Baking temps for removing moisture: PLA 45C, ABS 60C, Nylons 65C. Generally 3-4 hours will do the trick for most filaments, although some Nylons can take twice that long.