How can you tell if grout is sealed? If you press a wet finger to it, will it make a mark, absorbing the water?

Sealed grout will make water bead up. If you are in doubt then it can't hurt to seal it yourself. All About Grout | Tile | This Old House - 1 (http://www.thisoldhouse.com/toh/article/0,,384695,00.html)

Yes - but please do not use that "spray on" sealer! You do not need to inhale more then you apply. It may seem easier, but safety is more important.

Sealed grout will make water bead up. If you are in doubt then it can't hurt to seal it yourself. All About Grout | Tile | This Old House - 1 (http://www.thisoldhouse.com/toh/article/0,,384695,00.html)

I should have been more clear: I hired someone to clean the grout and tile in my bathroom, then seal the grout. I don't think it is sealed. The water doesn't "bead up" on the grout--it appears to be absorbed. When I press water against the grout, a dark mark is left at that place. I think I paid for a service that wasn't done.
Hemingway

What you describe I woud agree, paid but got nothing. Call the person back and have them show you what they used.

How long ago was the sealing supposedly done?

Grout sealers are not intended to make grout waterproof, only to help in preventing staining substances from penetrating the grout. Their ability to prevent stains is more like a small buffer to allow an opportunity to get the staining agent cleaned up, but if left on the grout, it can often cause a stain anyway.

Sealers are a base into which solids are solvent and when the sealer is applied to the grout, the solvent evaporates away, leaving the solids in the small pores of the grout. This is an over generalization, but for the sake of explanation, it works. A more expensive sealer has many different sizes of solids. Imagine a 5 gallon bucket and you fill it with some big rocks. Full, right? Well what if you then throw some pea gravel in there? Oh, lots more room than you thought, filling in all that space between the bigger rocks, huh? Seems full, but now it will still fit sand. Cheap sealers are like the bucket of large rocks, expensive sealers are like the buckets with rocks, gravel course sand and quarry dust. No matter how you packed the bucket, they will both let water pass through though, and sealers are specifically designed to allow moisture to pass, though it will obviously take much more water to penetrate as deeply into the later bucket. If your grout darkens after it's been sealed, it's not to be unexpected.

You could ask the cleaning/resealing person which exact sealer they used. No matter how many coats of cr@ppy sealer they use, you'll never get the kind of protection you wish for.

How long ago was the sealing supposedly done?

6 weeks ago

Grout sealers are not intended to make grout waterproof, only to help in preventing staining substances from penetrating the grout. Their ability to prevent stains is more like a small buffer to allow an opportunity to get the staining agent cleaned up, but if left on the grout, it can often cause a stain anyway.

Sealers are a base into which solids are solvent and when the sealer is applied to the grout, the solvent evaporates away, leaving the solids in the small pores of the grout. This is an over generalization, but for the sake of explanation, it works. A more expensive sealer has many different sizes of solids. Imagine a 5 gallon bucket and you fill it with some big rocks. Full, right? Well what if you then throw some pea gravel in there? Oh, lots more room than you thought, filling in all that space between the bigger rocks, huh? Seems full, but now it will still fit sand. Cheap sealers are like the bucket of large rocks, expensive sealers are like the buckets with rocks, gravel course sand and quarry dust. No matter how you packed the bucket, they will both let water pass through though, and sealers are specifically designed to allow moisture to pass, though it will obviously take much more water to penetrate as deeply into the later bucket. If your grout darkens after it's been sealed, it's not to be unexpected.

You could ask the cleaning/resealing person which exact sealer they used. No matter how many coats of cr@ppy sealer they use, you'll never get the kind of protection you wish for.

What a terrific analogy. Thanks for the explanation.

Bijack offers some good information.

After the grout is sealed, not getting it wet for a period is a better for the product. So, if you didn't get the area wet just after application, then it should be doing it's job. Did you call the person who applied it? Ask them what product they used.

Sealer does help with staining as Bijack mentioned. The only place I suggest to use sealer now is in wet shower bath areas and around area's that are going to be easily stained. It does help with water, but not entirely. More grout products have additives that help with water penentration now.

Sometimes the grout used, may have been sitting on the shelve for too long, or be defective as well. Not sure you had grout applied recently.