ὃς δή τοι εἶδος μὲν ἔην κακός, ἀλλὰ ποδώκης
These two characteristics are contrasted, one negative (ugly) and one positive (swift-footed). The phrase εἶδος … κακός is analogous to the more frequently used constructions for being good-looking, such as εἶδος ἄριστος / -η (Iliad 2.715, 3.39 = 13.769, 3.124, 13.365, 13.378, 17.142, Odyssey 11.469 = 24.17) and εἶδος ἀγητός / -όν / οί (Iliad 5.787 = 8.228, 22.370, 24.376, Odyssey 14.177). Compositionally, it is most like Odyssey 11.469 (= 24.17), which is also a relative clause with ἔην between the noun and adjective.
When we think of Homeric heroes who are explicitly labeled ugly, the first to come to mind is Thersites, who is described as “the ugliest man who came to Troy” (αἴσχιστος δὲ ἀνὴρ ὑπὸ Ἴλιον ἦλθε, Iliad 2.216). We know that αἴσχιστος refers to his looks in particular because the next three lines expand on this adjective with details of his physical appearance: he is bandy-legged and lame in one foot, his shoulders hunch over his chest, and his head is pointy, with sparse hair on top (Iliad 2.217–219). He is especially hateful to Achilles and Odysseus, two preeminent heroes of the epic tradition (Iliad 2.220). Of course, Odysseus has a bitter encounter with Thersites in Iliad 2, and we know from Proklos’ summary of the Aithiopis that Achilles will eventually kill him in anger. Indeed, although we are told by the narrator that Thersites is a source of laughter (γελοίϊον, Iliad 2.215), and in his lameness he might be thought similar to Hephaistos, whose bustling provokes laughter (Iliad 1.599–600), Thersites provokes anger from the Achaeans (see Kouklanakis 1999). Dolon’s ugliness, by comparison, is not dwelled upon, and does not seem to provoke any particular strong reaction, whether ridicule, repulsion, or irritation (see, however, 10.400 for Odysseus’ smile and 10.446 for Diomedes’ glare as their reactions to Dolon upon his capture). Yet pairing Thersites and Dolon based on their looks might also suggest that, in the Iliad, Odysseus, whose own appearance is not unequivocally impressive (Iliad 3.209–224), seems to have the role of confronting ugly men (but in neither case is he their killer).
In contrast to his bad looks, Dolon does have the positive attribute of being swift-footed (ποδώκης). For a traditional audience, as well as for us, the epithet “swift-footed” brings to mind Achilles, of course. Achilles has two other “distinctive” (in Parry’s terms) epithets that indicate his swiftness, ποδάρκης and πόδας ὠκύς (Parry, MHV 64, 145), but he is also called “swift-footed” with the adjective ποδώκης twenty-two times in the Iliad and twice in the Odyssey. In addition to Achilles and Dolon, the adjective is also used for horses four times (in one of these cases, it is applied to the horses’ drivers in an apparent transference of the epithet). So, here, the epithet evokes both Achilles and horses just before Dolon asks for Achilles’ horses as his reward for undertaking the spying mission (10.322–323). Achilles, we know, is the best looking of the Achaeans, as well as the best overall (his horses are the best as well, see Iliad 2.769–770), and the trait of swiftness that Dolon shares with him heightens the contrast of Dolon’s ugliness. As we will see below (10.330), there seems to be a prohibition on the taking of Achilles’ horses by his enemies within the Iliadic tradition, and Odysseus’ reaction to Dolon’s confession that he has been promised them also points to this contrast: Dolon is like Achilles in being fast, but he is no Achilles. Like Dolon, however, Achilles is also involved in ambushes at night (see e.g. Iliad 21.34–39 and “The Poetics of Ambush”). Achilles’ swiftness has been understood as an important quality in battle, and it may also be so for ambush missions. If this is the case, Dolon’s swiftness will likewise be important for the spying mission he volunteers to undertake. We will see Dolon run, but he is outsmarted and overtaken by Odysseus and Diomedes. In one of his Cretan lies, Odysseus claims to have ambushed and killed Orsilokhos, a son of Idomeneus, in Crete, and he says that Orsilokhos is swift-footed, faster than all other seafaring men in wide Crete (Odyssey 13.259–270). That story provides another example of the victim of an ambusher being swift. It may be that the strategy involved in ambush is traditionally associated with overcoming physical talents, such as being a fast runner.