My understanding of lateral plosion is Best Before End June 1974, but as I understand it a dark L is what you get at the end of 'leek' rather than 'little'.:
Originally Posted by alienvoord
In fact, the closure for the /l/ phoneme is a long way forward in 'little': the tip of the tongue is busy making the closure for the /t/, and all the speaker does to achieve lateral plosion is release pressure laterally; I don't think it's dark at all.
dark L - closure at the hard palate
clear L - closure at the soft palate
lateral plosion (some people put a schwa in there, but I don't - unless I'm imitating the Goon Show - Bluebottle certainly said /'litəl/, but he also labialized the final /l/.)
But if your book talks about /l/ with lateral plosion as being intrinsically dark, so be it; it just seems to me to be missing a trick, according to my memory of this stuff.