It's not the confiscation that's the problem in and of itself. If they have poor stealth packing that makes them a worse choice than a company with better stealth packing methods. Also, some companies offer free reshipping if it's confiscated with stealth packing (Herbies and Attitude both do, for example). While shipping the seeds and saying "Godspeed, it's not our fault if they get seized" may not make them a shady company, the risk has to be factored in to your purchase.
Seeds aren't cheap; at the best of times they're at LEAST 4 or so USD per seed, and often more (frequently double this amount or higher). Getting just a handful of seeds can run over 100 USD in short order, and shipping is never cheap (except with Mephisto, since they offer free shipping!). Buying seeds is a significant investment for a potential grower, and the myriad of risks with cultivating cannabis mean that we have to be VERY discriminating. The sad truth is, only companies with the very best methods, prices, and longest lucky streaks are going to get the best reviews and repeat business. Any seed shipment can get confiscated by customs; it's how often it happens and what the company does about it that determines how we regard them.