I have purchased multiple pairs of these dumbbells and intend to purchase more soon. Regarding the common complaints, let's address them here:
THE WEIGHT: An online search shows that it is extremely common for hex dumbbells to have slight weight variations; most manufacturers specify an approximate weight tolerance of +/- 3%. For Example: this means a 50lb dumbbell could actually weigh anywhere from 48.5 lbs. to 51.5 lbs. and still be considered "well within spec" for mass-produced fitness equipment. From many of these reviews, Amazon Hex Dumbbell's are only around a 1-2% tolerance, that's pretty damn good.
THE SMELL: These things are rubber and yes, they are going to have a rubber smell, all rubber hex dumbbell's do when new and are coated with an oil during the manufacturing process. Put some dawn dish soap in a bucket with water, wash them, dry them and the smell will go away quickly. This will also remove any of the oil from the manufacturing process.
SCUFFS: I can understand the complaints regarding deep gouges, chips, cracks and any significant damage during shipping. I am just surprised at the reviews mentioning slight scuffs from shipping. Come on, you are going to scuff these things up using them over time anyways, get over it. Put them to work and use them to get the results you bought them for. You didn't buy them to let them sit unused and look pretty, they are weights.
Overall, I am extremely happy with these dumbbells, and for the price you can't beat them. They are great quality and easily compete with dumbbells that are double the price. For what they are the price is pretty unbeatable. Hopefully this review helps you out and covers any concerns you may have.