Heck, I know of sign shops that purposely give wrong information, just so the competition costs out wrong when the possible customer shops your drawings and quote sheet around. So many shops won't go out and do a physical survey and ask for the competition's spec sheet, just to get around what you're complaining about.
Had this job about 20 years ago, where a company asked me to make said signs and gave me all their specs. I found out who made them and since the place was somewhat close, I went out and checked them out. There were about 10 or 12 signs involved, some cut-out letters, some channels and one large electric double sided sign. Sure enough, all the measurements were 2" to short in all directions. What that does is, in all signs requiring replacement faces, the size they specced would fall right out, as the retainer would not hold them at all. The cut-outs had to fit in a special area and it too, was too small. However, the channels were too large and would not have fit had we used those measurements.
It's a shame people do these things, but if you feel you must leave information off your quotes, then so be it. Unfortunately, an uninformed customer is not a healthy scenario.
