The "red" thing was really hot a couple years back (especially on the freshwater scene). Red hooks, red tubes, red jigs, red blades, etc. were being marketed by every major manufacturer. It's not really a new idea though. Plugs with a splash of red under the "throat" and bucktails with red thread wraps have been a staple for decades.
The two popular theories for using red are:
1. It imitates blood, and thus a wounded baitfish.
2. It imitates a phenomenon known as gill flash, which indicates a frightened baitfish.
Both are plausible. However, you have to keep in mind that if it is a factor, it would only be so in fairly shallow water (less than 15') as red is the first color to "disappear" in the water column.
