Contractions again (I am sorry)

I took a look through the archives and the Apostophe thread and didn't really see what I am looking for so I aplogize in advance if this has been covered.

I work in an advertising firm and today someone submitted an ad to me which said: "Come on over the water's fine."

While this "seems" to follow the rules of: using the apostrophe as the missing letter for clarity, my instinct tells me that there is something wrong here.

Can I really make a contraction out of any word that I please?

My shirt's dirty. [shirt is]
Your lunch's nasty. [lunch is]
That dog's eating something gross. [dog is]

It just doesn't look correct, but after our office argument about the correct use of an apostrophe for a contraction I thought I might just look for the answer from a pro.

Great site.

Thanks

Hi,
interesting question. I recently started to wonder if "Mike's here" was ok instead of "Mike is here." I mean, maybe not in written English, but I was even unsure about spoken English. Then I decided to take a look at my book on pronunciation, and I found something like:
The dog'll've eaten 'em.
So I thought, oh well, I think I shouldn't be afraid of contracting a simple "s".

Yup, we contract lots of words in spoken English. 
- That'll be the day. 
- He wouldn't've come if it'd been snowing.
- What'd you've done?
- When'd you see 'im?

But we don't actually write all of the contractions we use when we speak.  There're only a few that are commonly written.

A feeling of "spoken English" is exactly what the advertisement is trying to achieve --  it should sound like a spoken invitation because that sounds warmer and more personal than a formal written invitation.

Kooyeen wrote:

Well, for example, I don't like "Your snack's nasty", (I do.) but I would say "Your dinner's ready". (Me too.) That's like "Mike's here". (Sounds fine to me.) I'm not sure the contraction "s" sounds good after a voiceless sound, because it'd () be pronounced as an "s" sound (The 's' sound is good. You don't have any trouble with "it's", do you?) (Mike's here, your snack's nasty). On the other hand, I like "s" after voiced sounds, it sounds like "z" and I'm more likely to contract it (Your dinner's ready). Go figure

Contracting a noun with 'is' basically ends up sounding the same as the plural form of the noun. Trying to contract 'is' and a noun such bus, watch, lash, box, etc.(i.e. you add 'es' to form the plural) would also end up sounding like the plural.  So,  trying to say "The watch's broken" would only end up sounding like you were saying "The watch is broken."

Bokeh, I completely disagree with "adverts very rarely take any punctuation whatsover."

Go open the closest magazine and tell me what you see.

I have been involved in the creating of paid advertisements and I assure you, they had punctuation. Perhaps Nona would like to chime in, since this is part of her business as well.