Now that Guided by Voices are back in (some kind of) business, will Robert Pollard finally shelve his numerous side projects? The latest from Boston Spaceships — the singer’s typically disheveled power-pop trio with ex-GBV bassist Chris Slusarenko and drummer John Moen of the Decemberists — suggests so. As always with Pollard, there are flashes of retro-rock quality here, such as “Chevy Marigold,”a Stonesy white-soul ramble with wailing female backing vocals. But to call some of these 26(!) word-and-riff bombs unfinished would be charitable; a few even seem unwanted.