Go for it, I bought a bin cleaning business 12 monhs ago off a guy up here who had 1200 customers on his books, he didn't like doing it in the winter months and wanted to sell up. I bought it just as the 3 months of icy winter was finishing last year and got it for a VERY good price

We now have 1650 bin customers and do them on a 4 weekly basis. Around here the general waste bins are only emptied every 2 weeks, so I have two part-time guys who now work for me solely doing the bins every other week.
We use a Berlingo van and bespoke 300ltr bin cleaning trailer that has a hydraulic lift on the back for tipping the bins, it can tip both normal 360ltr bins and also the large 1100ltr roll tops so we've also picked up a good few commercial customers as well.
All in all it works well for us and makes a good margin.
Our biggest day is 230 bins.
The majority of our new customers have come from our established window cleaning customer list so I would say they are the ones to target first when trying to establish a new venture.
Hope it goes well, feel free to email me or call if you need any further help.
We also have a flyer that works well for us and you're welcome to plagurise!