No easy way to get rid of water spots. You are correct about the spots being etched into the glass. Spoke to a detail shop not long ago about this same issue on our vehicle. No easy way to do it. Use a mild abrasive that's suitable for glass or plastic and rub away. The detail shop say's they charge $60 PER WINDOW to do it so you know there's more to it than just squirt some magic stuff on the windows and it'll go away. Don't know what the film might be for sure. I've heard RainX can cause something like that to happen. Use isopropyl alcohol is supposed to clean that. If it's any consulation to you, we bought our vehicle brand new, sprung for the paint treatment, kept it in the garage, cleaned regularly. Still developed water spots all over the thing. Just happens I guess.

These water spots are the price we pay for acid rain....
One man suggested using the finest steel wool possible (0000 ?) to clean glass...
Try this steel wool on a low visibility area...

We live in a city, with a nearby aluminum foundry, so our air is not the best. Fluorine is known to be corrosive to glass. Is there a source of fluorine emissions in your area?

Cleaning some home windows here facing a courtyard area.. the irrigation system mist from shallow well water evaporates into some kind of mineral deposits or something... They always looked like they had soapy smears or something.. nothing seemed to clean that whitewash look.

Discovered 3m scotchbrite sponges cleans them in an instant. Have to replace the scrotchbrite sponges frequently ... wears out the gritt. Doesnt seem to scratch the glass. Makes life easy.

Check this out: You live in California. You have 3 days. Take it back. They have to accept it back.

is this on the outside or the inside? if on the inside it sounds like residue left from tinting film. if thats the case a clean rag soaked in some spray carb cleaner will clean it up, just keep the doors open when using it.

If you do have a three day right to cancel your agreement to buy, that's something to consider, but I've never heard of a law allowing that in the case of a private sale. Dealer sales, yes, but not when a vehicle is bought from a private party. It would be worth a call to a local attorney or your state consumer affairs office or attorney general to find out, though.

Bill_h is right, if it's oily dirt, water and most window cleaners will just smear it around and make matters worse. You need something with petroleum distillates in it. I've never tried the carb cleaner but that would probably work. You may also wish to try "bug and tar remover." Do not use any water until you've cleaned the windows completely with the cleaner. (Water does not mix with petroleum-based cleaners and if you put water on the window, you will make the cleaner far less effective.) Be sure to use in a well ventilated area, as he said, and keep away from flames or any possible source of sparks.

Try a mix of dishwashing soap laced with household ammonia. Use rubber gloves to protect your hands from the de-greasing effect of the ammonia. If the glass is pitted or etched, cleaning it will not remove the haze cuased by the pitting/etching. This will have to be polished out, or the glass replaced.

Thanks for all your great advice - I appreciate you all taking the time to respond. I shall try some of your tips. I have also been scouring the net for advice on this and found quite a few glass polish products:

-One Grand paste glass cleaner
-Autoglym glass polish
-Sonus glass and chrome polish
-Janvil glass renew
-Eastwood glass polish kit
-Cerium oxide powder

Has anyone used any of these? The Eastwood kit includes a buffing wheel for a drill and I'm a bit leary of using that kind of force with little skill and experience. The other products appear to be 'slap it on and rub' creams though.

As for private party sales, it's 'buyer beware' (which, of course, I thought I did:(). I am hopeful I can make it look a bit better - if not, I guess I have to live with it.

If you are unable to clean your windows with any of the suggestions above, then they are very likely etched, and the Eastwood kit, using cerium oxide or some similar abrasive, is your only remaining solution. You will need to use a drill, or some other power source, to speed up the process. It might take 4 hours to do a single window.

Possible clue?

Many years ago I was a relief driver on a truck where the 2 regulars smoked like chimneys. The windshield was so smoked up it was hard to believe; like driving thru light fog. None of us relievers ever found anything to cut that tar. I spose it was an inorganic (ie vegetable) type tar and organic (petroleum) solvents might not touch it. Could that be your problem?

I posted this a couple months ago and I know it works as I've used this technique myself.

Here's something shown to me by an Auto detail guy, He's been in the Business for 20 years that I know of so I was interested in his advice on clean windshields. Get some Steel wool, # 0000, or super fine, and pick up some Automotive Cleaner-wax. Take a piece of the Steel wool and put a generous amount of the cleaner on it AND the Windshield, now VERY GENTLY use a swirl or circular motion and "polish" your windows, after you do an area you just buff it out like you would a cars painted surface. Take your time and do small sections at a time, I generally do mine in 1/4's. After you have buffed your windshield clean, use some Rain-X and give it a coating. You'll be amazed at how clean it comes out, and the Rain-X not only helps with water but also bird droppings, tree sap, etc. I know this sounds like an invitation for tons of scratches and I was skeptical until I watched this guy do it on a customers car. I've been doing this with my windshield for at least 10 years now, and not a single scratch. Hope this helps.

If this is on the inside of the windows.I would be more worried that you have a bad heater core then messed up windows.

A note of information:

Cerium oxide can be purchased at rock shops (lapidary), and the cost per oz may be less than an auto supply. Cerium oxide is a popular final polish for rock tumblers, and the final polish for gem cutters for stones of hardness Mohs 7 or less. (Glass is about 5 on the Mohs scale; Quartz is 7.)

Cerium oxide of itself does not stain, but it can invade fabrics and is very difficult to remove, so try not to get any on the uphosltry or your clothing.