D&D General Why do we color-code Dragons?

[Staffan]

Those claiming that kobolds were originally dog-humanoids can note that the AD&D 1e Monster Manual:

I wonder how much of the association of kobolds with "dog men" comes from the original Baldur's Gate CRPG, where you run into plenty of kobolds early in the game and they have the war cry "Yip yip!"

Why did kobolds get dragonized in particular? Well, the 3rd edition Player's Handbook mentions on p.49 that . . .

. . . and in addition to speaking Draconic, that seems to be all the suggestion that was needed. Mongoose's Slayer's Guide to Kobolds in 2003 seems to have all kobolds claiming a connection, and by 2006, WotC's Races of the Dragon includes kobolds.

In addition, you have the Best Kobold in the Sunless Citadel, Meepo, who has managed to hatch and intends to train a wyrmling white dragon (who is one of the strongest creatures in the whole module). The wyrmling is not cooperating with Meepo's plans.

 

[Tonguez]

The first time the monster entry for kobolds for any version of D&D mentions "dog" or any variations on it was Moldvay (using calling them "small, evil dog-like men") -- but it's also the first entry that the text explicitly establishes their skin as being "scaly". It is understandable that readers starting from Moldvay, Mentzer, or the Rules Cyclopedia could notice the "dog-like" and miss the contradicting "scaly" (and I note JRPG depictions of kobolds probably start from the Japanese translation of the Basic Set), but D&D 3rd's Monster Manual didn't actually change what kobolds were in D&D lore. Starting with the original Monster Manual, kobolds were consistently land-dwelling, hairless, and scaly,

Scaly skin is a common description of eczema and similar dermatological conditions and importantly scaling is a common issue for Chihuahua and similar hairless dogs - so really saying they had scaly skin doesnt suggest reptilian traits at all, and paired with dog-like makes me think of Kobolds as vicious little Chihuahua people.
I will concede that the egglaying thing is a significant push towards being reptilian

 

[Paul Farquhar]

I wonder how much of the association of kobolds with "dog men" comes from the original Baldur's Gate CRPG, where you run into plenty of kobolds early in the game and they have the war cry "Yip yip

None, directly. BG1 was referencing Basic D&D lore, some of the kobold rumours are direct quotes from Keep on the Borderlands.