What bothers me about the ads is their use of the Bacardi Orange “O” for a logo.
And here it is again from the Bacardi site, but you have to say you’re 21 to see it.
No they don’t. They simply ship the money off to Denver, just like the bookstore down the street does.
Just as unconstitutional as what? Sales or use, either way, it’s a tax on a purchase of something I bought to use in Colorado. The reason they’re not rigorously enforcing it is because it’s not worth it. If and when it becomes worth it (the dollars collected would be more than the dollars spent making the collections), then it will be enforced more severely.
I’ll chime in and say I’ve had no problems at all with the 15+ orders I’ve placed with overstock.com over the last couple years. Most of what I order is books or linens though, they have some great deals on nice sheet sets. 
I got a good deal on a necklace as well, but it pays to do some price matching if you see something that you like. The cheap and fast shipping is a big draw for me as well.
A “use” tax is something charged to you, for your “use” of that product in your State. You have to report that on a special form- or sometimes you can add it on to the bottom of your State taxes.
If an Etailer in another State charged you that tax, and mailed it off to Denver, Denver would still think that you owed it, since there is no record of you having filed and paid that tax on that “use”. YOU owe the use tax.
Sales taxes are owed by the retailer- not you. The retailer may (but sometimes doesn’t) pass that amount along to you. That’s how they can get away with “Sales tax free” sales. THEY owe the sales tax. A reatiler in your State likely has a 'sales tax permit" allowing them to pass the taxes along to you- that’s how it works in CA, anyway. The Etailer in another State will not have a 'sales tax permit" from your state (or mine) allowing them to collect sales taxes from you.
There is no legal “sales tax” on INTER-state commerce- per SCOTUS. Only INTRA-state commerce.
Got it?