I am responding as somebody who lived in the Sunnyside neighborhood of Linden for 8 years, and later lived in Rahway and still had occasion to visit Linden frequently after moving out of that town.
Yes, Linden is a heavily industrialized town, but the Sunnyside neighborhood is at the extreme southwestern end of Linden, and is actually several miles from the industrial areas that lie east of Route 1 & 9 and in the vicinity of the turnpike. As a result, Sunnyside isn't really "smelly" as the prevailing winds almost always take the stench of the refineries (note: there is no apostrophe in the plural of "refinery") over toward Staten Island. Sunnyside is essentially an area characterized by well kept-up smaller single family homes, with nicely maintained front yards.
If somebody chooses to live in Linden, the Sunnyside neighborhood is definitely the best neighborhood in the entire town, and it is--to a great extent--indistinguishable from the adjacent parts of Rahway and Clark that border Sunnyside. If you didn't see the signs announcing "Entering Clark" or "Entering Rahway", it is unlikely that you would realize that you had left Sunnyside. That is how similar they are.
That being said, over the past decade or so, the crime problems of Elizabeth and--to a lesser extent--Roselle, have crept into Linden. The good news is that the parts of Linden that are most affected by this spill-over of crime are adjacent to Elizabeth and Roselle, and Sunnyside is much less affected than the more northerly parts of Linden. However, the fact remains that the overall crime rate has risen over the past decade or so.
Another factor to consider is that Linden's schools are...not the best. While they are not in the same bottom-of-the-basement category as the schools in NJ's inner cities, the fact remains that they are below-average in quality, when compared to schools statewide.
Yes, I can think of many places to live that are better than 21st Century Linden, but at the same time I can think of many neighborhoods that are
far worse places to live than the Sunnyside neighborhood of Linden.