Monitor Quality - who to Design for?

Question

I put a kind of watermark/hover image on a site not long ago to add content the owner inisited on but I thought didn't help the look of the page.  We went back and forth, and all the time the site owner kept asking for it to be darker, darker, darker...  Eventually, it wasn't a watermark and it was abandoned after a shed-load of work.  Recently, same site-owner looks at a graphic and asks to tone it down but this time, we're looking on my monitor and he's happy.  Then I get an email asking for toning back up a bit.  It's really not that important but I'm begining to suspect that it might be a monitor problem but this time I just said no.
So here's the question.  Maybe I'm wrong to design to my studio monitor which is high(ish)-end and color-managed?  It's one thing to try to design to different size/resolution of monitor but now I'm thinking quality and set-up too!
Martin

Answer 1

Thanks both.
I think what I am suffering from here is working for a person who has no idea about the web or computers (after 200 emails between us, why should he?).  I think I'm learning a few customer relations pitfalls er..
...I mean, opportunities!
This website seems to have been built by a series of tweaks and before you know it, the work load has doubled.  Still, I'm teetering on the edge of a rant here so, back to the point.
It's not just about color profile Paula, it's about the monitor's ability to even show detail.  I think that a design can look really graceful with careful use of images, borders, grads and color but, I've realized that not everyone will see the effect if it's very subtle.  My watermark came about after designing and after the request, "Can we put a sample of every image on the front page thingy?"  I stuck in a row of thumbs to kind of show how it awful it would look and guess what?  It got approved!  I tried for a compromise and added the row as a row of very pale grayed out images and a full-color hover and, kept getting the darker, darker, darker until I'm in it up to my neck and hours of work have passed me by.
Oh, I don't mind so much.  At least it gives me something to do whilst I while away the hours, days weeks waiting for content!  I think that what I learned most, is that some components of a page might not show on a poorly adjusted or inferior monitor, that that might have some accessiblity implications and that it isn't just text that needs contrast.  On my 26" HD screen that's color managed it all looks so lovely but....
Ah well, a few more tweaks await.
Martin