My wife and I moved to Padre Island 3 years ago. The smell your talking about in the area is the sea grass you see along the shore as your driving from Floue Bluff to the Island. The strength of the smell comes and goes, but it is the natural result of decay. To address the beach question. The weed, as it is called, comes in around March to May. How long it stays depends on a lot of factors, ie. water currents, water temps, number of storms in the Gulf, etc. Usually the weed clears in the fall when the water temps start to drop.
The weed is a mess on the beach and we always take a shovel and rake when we go to the beach. The city and county do a good job of scraping the weed and this process helps build a great foundation for the dunes. Also the weed, while it out to see is a great home for sea turtles, crabs and small marine creatures to live and escape fish. The best news is that as the weed comes into close shore a lot of big Red fish, Trout and Shark swim in the weed looking for dinner.
To sum up. If your going to live on the Island and enjoy the beachs take something for your sinus', a shovel, rake, and enjoy the fact that we live and share in a great enviroment for wild life. Other wise Destin Fl. would be the place to go if your wanting a pretty beach, snow white sand, and not much wildlife.
FYI: Big Reds are in the weed off the Packery Jetty now hitting on 3" live mullet. I saw a couple of nice size fins also. So take some Shark tackle and have some fun.
Call me if I can help you with your real estate needs. See you on the beach