Yes, they are very good at marketing, and have used their prowess in this regard to build what I assume is one of the largest speaker and related-products company in the world. They are targeting the mass market, not those who buy based on sound quality (which is a relatively small niche market). Bose is a great case study for the power of brand-building; the market they've targeted overwhelmingly believes that Bose = best. Combine their brilliant marketing with their low cost of manufacturing (ever look at a Bose driver?), and you've got a recipe for a market juggernaut.
One of their most brilliant marketing tactics was the concentration on auto sound systems, which they sold relatively inexpensively to auto manufacturers in return for prominent brand placement (but still at great margins, given the low cost drivers they typically use). This strategy dramatically expanded recognition of the Bose brand, and further positioned them as a "premium" product.
Only the small portion of the marketplace which prioritizes sound quality would argue otherwise. This small market cannot support the expense of mass marketing campaigns, and the speaker makers who focus on serious listeners generally don't pursue product line extensions (headphones, packaged surround systems, countertop sound, etc).
A notable exception is Harman International, which attempts to cover the entire marketplace, from convenience/lifestyle listeners to audiophiles, using a range of product lines and brands. I would guess their marketing budget is not insignificant, but it is somewhat diluted/fragmented by the need to support multiple brands in multiple segments.
Bottom line, the enthusiast/audiophile segment is small, it has different purchasing criteria, and it is not targeted by Bose. The companies who do target it are inherently small, given the small and fragmented market, and must survive on relatively low volumes. They therefore must have high margins (and high prices). In turn, this benefits Bose, which through their successful efforts to position the company as "high end", are able to demand the premium prices inherent in the audiophile segment, but with dramatically higher margins.