I don't think that is possible to set a background color in a way that you hide any text on a text ad -- if the colors get too close (text color and background color) the system overwrites setting a fixed color for text and it will always be visible. The only thing that I know that is against TOS regarding this is that you can not use elements on your site to hide part of an ad.
It's not possible to hide "Ads by Google" thru color adjustment, you can't decide it's color so it autosets to an opposite color, however i guess he/she's talking about the google_url_color which is possible to hide, but surely against TOS.
I don't think you can do that and even if you could, don't do it as it's not allowed. Google puts that link there for a reason, if it was allowed to not be shown the the general user then whats the point in them having it in the ads. Saying that though, google theirselves hide a partial bit of the link in some of the ad formats because they are not big enough for all of the ad.
Yes it is possible Have a look one of my blog http://parishiltongallery.blogspot.com/ I made link colour and background colour same...
If you mean the www... part in the ad, it doesn't show it on 468x60 if there's a 2 line description in the ad no matter what color you've chosen, if you use a box or leaderboard you'll see there will show the URL's.
Please come point... My doubt is this hiding Link, by choosing background colour is against google tos? what ever the ad format is...
Besides the fact you can't actually hide it, if it were even possible, i'd think they'd make a "transparent" option if they allowed it be hidden, so it'd violate TOS is what i think. Last comment