I agree Marc.....Back to Demos....As a perfectionist whenever I record anything (except for the odd rough work-tape used just to get an idea over) I want to do the best job I can. This is more for my benefit and self esteem rather than for anyone else listening or any future prospective buyers. As you say however you never know who might take a listen to any demo you produce both now and in the future so everything you produce should be a calling card showing off your best side.
I know that a lot of people cannot produce their own demos and rely on others or pay demo studios to produce a demo for them. In that scenario you pays your money and takes your chance but if seriously pitching a demo to anyone you must make sure that the demo is up to the standard required.
The studio that I use has a philosophy that they do the best job they can on everything no matter what it is and nothing leaves or is considered finished till it is up to that standard. They will go the extra mile even unpaid to get things to that standard. When reputations are at stake you cannot take shortcuts or adopt a "Oh that will do" attitude. It takes a long time to build up a reputation but seconds to ruin it.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055