Although this forum is probably more friendly and realistic than most in appraisals, you need to take all "appraisals" with a grain of salt whether from a forum or a more formal appraisal company. In real estate, cars, or antiques, an appraiser normally has training, experience, and real data of past similar sales to use as a guideline, mixed with some opinion based on appearance and personal knowledge. Forum appraisals are mostly going to be opinion, although sometimes educated opinion. You won't find many real appraisals that list similar domain sales related to the subject, or a guide to help such as an auto blue book or public real estate sales records. IMHO, they really aren't "appraisals", but "opinions of potential value" if I may split hairs. Basically with a free appraisal, you get what you pay for, a quick opinion with no factual data to back it up.
I really don't know of any domain appraiser that will currently give you a comprehensive report of similar sales, availability of similar names and their development status, a report of the market conditions or competitors on the subject matter of the domain, etc. Some may actually search other available domains, overture numbers, and other hard data, but most will not for free. Just accept them for what they are...opinions.
If you think they are too high or too low, just consider the source and if you don't like what you hear, dig up some hard evidence yourself to support the value of your name. The more data you have the better you can justify a price to a buyer. Google page listings, pagerank, traffic, other TLD registration and development status, overture, and many other factors can help you support an asking price better than an appraisal by someone who probably has no credentials to prove their opinions really mean anything. Don't get me wrong, there are some very knowledgeable "appraisers" here, but the accuracy of appraising domain names is way more of an art than a science at this point. I've been doing this for about as long as anyone, and the prices of actual sales on dnjournal surprise me every week with some I think went cheap and others I can't believe sold at all.
I do agree and follow the rule that you shouldn't appraise a name unless you have experience with the subject matter, the market, the TLD, a similar name sale, or some other significant factor. Doing so only further degrades reliability and believability of what is appraised. However, it's pretty easy for most here even with little experience to spot the real zero value domain and make a comment. There will also be some who appraise for their own gain as well, since they may have interest in acquirig the appraised name cheap, have the same name in another TLD, or a similar name.
Personally, I think a more postive way to appraise would be to point out both the positive and negative points to a domain that either give it value or mean it may have none. Just throwing out a number doesn't help particularly the newbie understand what makes a name highly valueable or a loser. I guess my keyword for a true appraisal would be "justification".
