My resort uses the following ratings descriptions (in descending order of snow quality) - (with my translations in parenthesis):
powder (new man made or natural snow over any base depth)
packed powder (it's been groomed)
wet (it's raining)
firm (what most people would call solid ice)
extra firm (what most people would call unskiable)
shiny (you can see a penny 3" down)
glaciated (it's got the blue/green tint to it)
race conditions (for diehards only)
But seriously, East coast resorts south of Jay Peak rely on man made snow for a majority of their base depth. At my resort, the base depth has never been less than 95% man made in the 11 years I've worked there. It's virtually impossible for a resort to make the same amount of snow over their entire trail system and most of the time they specifically make different amounts of snow in different places for management purposes (e.g. more snow in higher traffic areas, banking snow in piles/rollers for use later in the season). The difference in snow depths at different places at an Eastern resort can often be measured in feet.
If you look carefully, you'll see many Eastern resorts reporting an "average" base depth. However, even if they wanted to be accurate, it would be very difficult to measure. Even if a resort calculated an average based upon how much water they have pumped/acreage of terrain + natural snowfall - evaporation&melt, there would still be a lot of guessing.
Regardless of whether it's a "lie" or a "guess", at each resort the reporting is usually consistent season to season. Once you've learned the pattern, the snow report is usually pretty informative. At any resort reporting less than a 3 foot base, you should expect to encounter bare spots and rocks somewhere on the mountain (e.g. mogul runs). Any resort reporting fresh snow probably got some, but if it's been windy it's pot luck whether any of it stuck.
Although my experience is that resorts are generally within the range of "darn close" to "creative" with their snow reports, I do recall one time at a certain resort whose name won't be mentioned (Powder Hill, CT) where they left the guns on in the same place for 2 weeks, then dug a 6 foot hole into which they placed a basketball player and a bikini clad model, took photos and thus proved a 6 foot base. The fact that a different camera angle would have shown bare spots did not deter them.
These days for every resort that consistently lies about their snow conditions, there probably a web site with someone's "true" reporting available. Links anyone?