But, do this: Go to Radio Shack and pick up a pack of crimp connectors. Take some Ancor brand connectors with you. Now compare the two. Actually, the Radio Shack connectors are so thin and poorly made that you shouldn't even have to have the good ones to compare them to.
The point isn't that all crimp connectors are made the same by the same manufacturer. Of course there will be cheap stuff, medium stuff, and good stuff. But in each case the product can be "aimed" at any market the manufacturer or distributor want simply by altering the packaging, color, etc.
I would hope that someone shopping for good electrical components for a boat (or anything) would have the good sense to look at a cheap, crappy connector at Radio Shack and know that it was not suitable for the application.
But when the breaker sold at the marine store is virtually identical, even down to the manufacturer's model number, to the same breaker on the shelf in the hardware store except for the packaging or perhaps the color of plastic used but has a price two or three or more times higher, I would think anyone with common sense would realize what's going on here.
Obviously you have to pick and choose your categories. In the case of a quality circuit breaker, buying the one at Hardware Sales for $a.aa instead of the exact same breaker (but in black plastic) at Acme Marine Electric for $z.zzz makes sense.
Buying a cheap, flimsy, under-counter RV or apartment refrigerator vs a stainless steel Isotherm may not make sense despite the huge price difference.
When I asked the owner of the marine electric store a long time ago why he bothered to carry items like the "marine" circuit breaker he'd shown me along with the exact same breaker sold at the hardware store, he said that he carries a stock of the "marine" versions of these components for the customers he gets that will only buy something for their boats that is labeled "marine" These people, he said, firmly believe that, regardless of whether it's a screw, toggle switch, circuit breaker, terminal strip, etc., if it doesn't say "marine" on the packaging it's not suitable for use on a boat. There are enough people like that, he said. to make it worthwhile to stock these items because the profit margin is so high.