Appraisals are one of the most popular places on a domain forum. Now some are really just looking to advertise their name and don't really care what anyone else thinks, while others do want to know what others think of the name.
They want to get opinions a lot of the time on a niche they know and expect the same. Many times that's not going to happen. If you know the industry chances are most who give an appraisal on your domain are not as familiar with the industry.
Other times it is someone who is really looking for educated business opinions that go deeper than just,"Hey what do you think Velky.net is worth ?"
This for the most part is like asking for instruction on your golf swing from a tennis coach. Most people giving opinions on appraisal sections have no branding or marketing experience, they may have no business experience at all. This leads to frustration from the domain owner and sometimes animosity.
There were two people that pmmed me over the last two weeks about names they posted for appraisal and could not believe the answers they got back. My first thought is I understand that feeling and secondly, why do they care ? If you don't know the credentials of someone giving you an opinion then the opinion means little imo. You have to spend some time and seek out those that will give you an opinion and understand what you are asking and what you want to do with the domain.
Another reason why asking for appraisals is a bad idea on a public forum is that the threads show up on Google. I had a guy ask me to broker some names of his, I contacted a potential end user who was absolutely in the same field, the next day the prospect replied back, "It looks like the domain experts have said this name was worth 0, tell your client I will give him $10"
Sure enough the appraisal thread was the third result on Google when you searched "domain.com" So now you have an appraisal thread working as a potential detriment to your sales efforts.
Get advice from someone who knows the topic, take some time and read. Figure out who will give you a little time in an email and understands the industry.
Best of luck.