There was a discussion recently on Style Forum about groupthink among we gentlemen of the interweb and spotted knit neckties are certainly an example of my own participation in herd behavior.
I'd worn maroon, black and navy knit solids for years, but after seeing a couple of posts of men wearing the dotted versions I jumped in the pool. I'm almost ashamed to admit that now I have three, with the two latest pictured here. The white one is for wear with a navy summer mohair suit, and the brown for tweed jackets (I've a pair of brown cotton socks with small pink dots to match).
Knit ties are ideal for travel as they are more resistant to rude treatment than conventional silks. The dotted versions are simply conventional knits that have had dots hand sewn across the surface in a contrasting color. And, at least until recently, a man was far less likely to see a dotted knit coming down the sidewalk at him.
Now of course they're popular and I should probably place mine in storage for a couple of years.