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If your marketing is generic, (no idea who you're writing to), only showcases product features, (rather than highlighting customer benefits) and completely disjoined from your brand, (not in the same colours, fonts or imagery), then you're basically doing a door to door job. Your results will be down to luck and your efforts in the recycle bin without ever being read.
Given the time and energy it takes to produce marketing materials, can you really afford to live on hope?
Generic says "we don't know who you are and we don't care". Product Features with no context show "it's all about us" and lack of attention to detail is really just laziness. If you wouldn't be delighted to receive what you're about to post (whether off or online), don't send it.
Your customers are not unknowns waiting behind closed doors. They're yours to learn about, inform, educate and delight. They are at least as smart as you and face the same time/energy pressures, so stop thinking about them as 'them' and start thinking about them as 'you'.
I can hear you crumpling up that flyer.