Should unconventional colors be avoided for lighting?
A quick search, however, shows other colors available to purchase. Concerning "to be seen" bicycle lights, should they be avoided?


Yes, they should be avoided.

First, off-colors might not be legal in your area.

Second, and more importantly, no one will know what it is.  If a driver sees a flashing red taillight, or what looks like a normal white headlight, that driver is likely to identify you and your bicycle.  Something like a blue light is likely to evoke a, "Huh?  What's that?"  Which means most drivers won't treat you like a known entity - something they need to avoid.  

And what do drivers (and cyclists, for that matter) do about things that don't evoke a familiar "must avoid" response?  You won't even register as being there.  Think about it - how many random items to you ride past all the time?  Do any of them really register at all?  Trees, mailboxes, plants, fence posts - they don't meet your brain's "must avoid" pattern, so you don't react to them at all.

You do not want to be cycling in the dark where you need lights so you're seen and safe, and then do any thing that makes it harder for others to identify you as a bicyclist.