Is this a 'what' or a 'who' ...

[AccountingDrone]

I know a handy trick to cheaply clean lace curtains and any metals that have encrusted filth; denture tablets! Fold the curtains neatly, and ensure they can fit in a basin of water with plenty of clearance, and plop in a few tablets. The effervescence loosens any dust or dirt without harming the materials. Repeat as needed.
Another great way to clean silverware/brass/what have you is steeping them in hot (not much point in it being boiling, but it wouldn't do harm) water with either vinegar, or the much more pleasant smelling lemon juice for about 15 min. Take them out and towel dry.
To get a really nice 'just polished' look, without much effort, use very fine steel wool, a little lasts for ages and you get it in giant balls. The finer the better, and it leaves metal shining.
tern, leave it sit for a little while, and then flush, you'll be disgusted what grime it picks up :P

Vinegar is really harsh, and should only be used neat on metals, ceramics and glass, and you really have to rinse well after. Do not use it on wood , epoxy/varnish or plastics as it can cause discolouration.

Please for the love of god Montressor .... PLEASE DO NOT USE THESE TECHNIQUES ON ANTIQUES.

<pant, pant, pant>

You have no idea how many times I have gone to antiques auctions with my Mom and her other dealer buddies and listened to them pointing out the damage done to the actual antiques [and their preserved value] by aggressive cleaning 'to spiff it up for auction so it will look better and sell better' I think one of the worse drops in value was a chippendale chair that someone took down to the bare wood and revarnished with synthetic high gloss varnish. Dropped it from almost $100K to $5K

Shall I say that it would be worlds better to contact a museum and ask them the best way to deal with any specific antique?

And PLEASE, NEVER EVER TAKE STEEL WOOL OR CHEMICAL CLEANERS TO METAL WITHOUT ASKING A MUSEUM OR RESTORER FIRST!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!

[Ashcroft]

Sorry AccountingDrone; I should have clarified about antiques being off limits... a lot of antiques lose value when cleaned, especially by untrained persons.

I'm training as a jeweler, and this is the kind of stuff we do for various finishes and fast cleaning. This is all low-end, easy solutions to possible issues for cheaper home products. Stuff anyone might have in their home.

Please only consider what I said for everyday, inexpensive products.

[Aethian]

Okay what above good silverware that's about 20 years old? It's not antique but it hasn't been treated the best since we finally found where the basement repair team put it since the basement got ruined.

[Ashcroft]

Depends on what it is and how badly it's affected.
if it's silver plated and there are grey-purple discolourations on the surface, it can't be fixed. That's an oxidation of the silver, and it needs to be removed and re-polished.
There are cheap ways to remove grime as I listed above (lemon juice and such) but you would still need to repolish the surface, as heat and acids cause silver to take on a matt appearance, and heating it too much can cause that discolouration I mentioned earlier.
Your best bet, take it to a jeweler for refurbishment and keep up the maintenance yourself after.
It shouldn't be too much work, and as such would be inexpensive, depending on how many items are involved. Even then you do do them piecemeal, say 10 items, whenever you could afford it, and bring them gradually back to a full, proper collection.

I forget that people don't have access to my experience at times, and quite a few little things matter when dealing with surface treatments of metals. So I'm reluctant to say what can be definitively done without having them in front of me :P