I am headed out into the field today (I should be in the field by the time this post drops) to record a site. The site is known, and a site record had been previously produced. However, the older record was of very low quality, providing little actual information aside from "there's a site in this general area...oh, and we think it's a prehistoric site."
This sort of thing is pretty common. There are many companies that produce solid work - good reports, good site records, and field and lab work that you can be pretty sure will be accepted by the agencies to which you have to submit the work in order to get your permits or money. My current and immediately previous employers were known for being these sorts of companies.
Then you get the low-ballers. The companies that will cut corners, produce a shoddy report and site records, and have dubious methodology. These ones get by by producing the "work" that they produce for a very, very low price. The work of these companies is usually a product of greed and laziness, but not outright corruption - though there are a few that veer into the latter category. If you happen to be submitting it to an agency that doesn't look to closely (or doesn't care) and if you are doing so in an environment where there is little reason to think that any public groups or private individuals will be scrutinizing it, then you can get away with this - and that's how these companies stay in business.
However, if you have a project that is likely to be scrutinized or where the agency reviewers aren't asleep at the wheel, there's a good chance that these low bid companies won't fly. Case in point - I am leaving today to go out int he field and re-do some work done by someone else. They issued a report that lacked the necessary background information, only vaguely described the study methods, and the site record that they produced along with the report gives no real information. The company that initially hired them paid about 2/3 what my company charges for the same services, which is why we didn't get the original contract. However, the report was rejected by the agency because it didn't provide any of the important information that the agency needs to comply with the relevant regulations. So, after some bickering with the first company, the client dropped them and hired us. Now, rather than pay our original cost, they have paid 1 and 2/3 of our original cost, and look bad to the agency from which they need to get permits.
So, the lesson is, if you are ever in a position where you have to hire an archaeologist, biologist, geologist, clean air/water person, etc. etc., don't just look at the price tag, look at their qualifications. It may save you some money in the end to not go with the cheapest one up front.