What are the limits to a half-dragon using the Disguise Self spell?

Question

My understanding is that a half-dragon can't use the spell disguise self to appear human. A half-dragon just has too many limbs for that to work properly, not to mention technically the dragon is no longer humanoid in type.

Type: Creature type changes to dragon. Do not recalculate hit dice, base attack bonus, or saving throws.

The disguise self spell says, "You cannot change your creature type (although you can appear as another subtype)."

Can the disguise self spell allow a half-dragon to appear as another Medium dragon, a wyvaran, a drake, or anything similar to dragons?

Answer 1

You can appear as a full Dragon, or another creature that is the Dragon type (including Wyvaran) as long as you conform to the other restrictions of disguise self. The spell is in no way restricted to Humanoid (except that Humanoids remain Humanoid, and other Types remain their same Type).

You can seem 1 foot shorter or taller, thin, fat, or in between. [...] the extent of the apparent change is up to you. You could add or obscure a minor feature or look like an entirely different person or gender.

So you could probably pass for a Medium Young metallic or chromatic dragon of your choice, but not a Gargantuan Great Wyrm.

---

Side Note: Generally speaking, Illusion spells don't care about things as paltry as number of limbs. Particularly, Glamer spells:

...changes a subject’s sensory qualities, making it look, feel, taste, smell, or sound like something else, or even seem to disappear.

If you were, say, an Alchemist with the Vestigial Arm Discovery, you could cover that up with disguise self or a similar spell.