I'll just add in that I've placed around 30 orders with Mouser over the past few years and have never really had any trouble.
I only ever order UPS 2nd day, because FedEx loves to find excuses to not deliver packages and UPS Mail Innovations usually makes packages disappear, and I don't really see a good reason to save a few dollars for the package to take 5 times as long to arrive.
The only time I had an issue was receiving the wrong color of LCD once. I can't really place too much fault on them, the manufacturers part number was very hard to read and differed by an easily mistakable letter. They gave me a $60 refund and I didn't even have to send it back.