LEE COUNTY, Fla.- Glass left unclean can become etched overtime and start to take on a hazy look. That's why experts say most homes should get a thorough window cleaning twice a year, ideally in the spring and the fall.

"Windows left unclean for long periods windows are porous and mother nature the mineral from things flying around can absorb into the pores of the glass and stain it permanently or it could take costly extensive measures to get that staining out of glass," window cleaner Matt Swales said.

You may also find that your windows need a good cleaning more often if you live on a busy street or near salt water. Salt sitting on the glass for extended periods of time will also cause damage.

The price of hiring a window cleaner is based on the number and size of the windows.. and also the time and complexity of the job. Always ask for an in-home estimate because each house will likely have a different price.

"If you are looking to save a few bucks you can still hire a window cleaner but consider dividing the job up. You can tackle the first floor windows that don't require special equipment. Leave the second story to a professional because they'll have the proper ladder," said Angie's List founder, Angie Hicks.

If you do clean your own windows make sure to do it during a cool, cloudier time of day.. the hot sun dries windows faster.. which can ultimately lead to streaking.

When hiring a company to do even part of your cleaning ask if they have a money-back guarantee of you're not happy.

Many companies will even offer a rain guarantee so if it rains during a certain time span and your windows are dirty again.. the company will clean again at no additional charge.

Use your best judgement on whether you're in the physical condition to clean your own windows too. Thousands of people are injured every year from falling from ladders while trying to reach to get the far corner of a window so sometimes its best to leave it to the professionals.