When someone talks about a persion doing a professional job, typically they mean that 1. the person is experienced, and 2. the person is familiar with and works according to the standards and practices in the industry.
Of course, all "professional" really means is, the person got paid.
In recent days, Walter Isaacson’s Steve Jobs was removed from the iBookstore and replaced with a new version because of formatting errors. One iBookstore reviewer wrote: “I want my money back. The formatting errors in the iBooks version are appalling. At first, a caption is missing or just a word, but it soon becomes illegible. The publisher should be ashamed.”
Similarly, the Amazon Kindle release of Neal Stephenson’s eBook Reamde recently made headlines because line breaks, missing passages, and hyphens preceding words such as “people” and “couple” were scattered throughout the eBook. One Amazon reviewer wrote: “…the reading experience is fatally tainted,” and demanded a full refund of the $16.99 price.
Think about that the next time someone tells you it's worth it to pay them $3,000 to format an e-book, because they are going to take good care of you--you can't even trust the large publishing houses (charging $17 a copy!) to do a decent job.
No matter if you hire someone (and you can do that for much, much less than three grand) or do it yourself, you need to read over the e-book before you publish it. And you can do that pretty easily even if you don't own an e-reader, just download Mobipocket reader to your computer to read a Kindle file, or Adobe Digital Editions to read a Nook file.
I know I've made this analogy before, but it is really just like dealing with a car mechanic or a home contractor: If you have no idea what the person is doing and no intention of checking the work, you will have no way of judging whether the fee charged is fair or if the work was done well. In other words, you will get screwed.