We've all had to tackle them at some time. The posh variants are cut-glass whiskey decanters. The less posh ones are kids drink bottles that have been left all sticky and full of bits after holding home-made fruit juice (what do you mean you've never tried making home-made orange juice with a simple orange squeezer?). Or you're washing out a flower vase that has been left a bit too long and has collected green slime. But there you are: you're trying to clean out some elusive scraps of goodness-knows-what, but the bottle or whatever has too narrow a neck to get your hand inside properly. What would a professional house cleaner do here. Or, if you are a professional cleaner tackling this job for the first time, what do you do?
What you will use as your first port of call is an ordinary bottle brush - the sort with a thin wire handle and bristles set in a spiral shape. With the help of whatever you ordinarily use for washing dishes by hand (Ecover makes a nice environmentally-friendly dishwashing liquid), put some water and the detergent of your choice. Then scrub around the inside of the vase, decanter or bottle with the bottle brush, which will pass easily through the narrow neck and then expand to gently reach the sides of the bottle, etc.
Bother - your cleaning efforts are thwarted by the bottle, decanter, etc, being too wide for the bottle brush to reach. Now what?
One easy method that has reasonable success for this sort of tricky cleaning job is to stuff a tea towel down the neck of the bottle. Make sure you keep a corner poking out of the neck or getting it back will be next to impossible. Then twist the cloth around and around the inside of the bottle, etc as best you can. It will be tough going. You can insert a long, hard object inside the cloth to help turn it in a sort of improvised big bottle brush.
But sometimes, the cloth won't turn or isn't abrasive enough. The old-fashioned butler's method, usually used for cleaning glass decanters, was to pour a little lead shot into the decanter, add a little brandy or whiskey, then swirl the contents around until the grime on the inside walls had vanished. Don't do this, especially if you plan on drinking out of the container or using to hold any sort of liquid that you plan to ingest, as lead is poisonous, and some will be left on the inside of the container, even after you've rinsed it. You can use this method for vases - the flowers are dead already. Use sand instead - it's lightly abrasive and will wash out easily.
If you don't have any sand on hand, you can try filling the bottle with dilute vinegar and leaving it to sit overnight. This will attack a lot of the gunk. Then fill the bottle with warm water and your choice of detergent and give the bottle a ruddy good shaking, holding onto it very securely. The motion of the water should flush off any remaining grime. And the real beauty of water for cleaning is that it can go into even the tiniest crevice.