The first thing anyone notices about Thom is his clothes.  His mundane clothes are a handmade imitations (though unless you look for copyright type symbols you might not notice) of the most comfortable current style.
His Chimerical clothing is almost flamboyant enough to make an eshu think that maybe he should tone it down, however even those who are into the most functional of garb have to admit that it always works with the rest of his appearance.
Like most boggans his eyebrows are enormous, and he tends to twirl them when having almost any significant emotion whatsoever.  His face is a teenage disaster though.  Large -- rarely oozing pustules of painful acne cover his face (and if you ever see them, much of the rest of his body as well).  His eyes are a bit too close together and his nose a bit sharp -- the overlay of that with his boggan rounded nose combine to become even less flattering somehow.
He is gaunt for a boggan, but normal sized for a human.  his hair is probably dusty brown, you'd have to check, it's so unmemorable, and it is unruly enough that he keeps it nearly crew cut short.

All in all the whole of his appearance cancels out.  His clothes might make a normal looking person quite attractive, but on Thom's ugly visage, they merely combine towards an average level, though not average at all, appearance.

https://fashionablymale.net/2017/04/25/pineda-covalin-fallwinter-2017-mexico-city/ for examples of his clothing.