Vinyl records grading scale


I am sort of new to vinyl and am building up my LP collection. A very prime source for it is the internet used market where appears to be sort of a grading scale system to rate condition of vinyl records on sale (G+-, VG+-, EXC, NM, etc). Is there any place I can refer to for the criteria or guidelines as to what to expect from the different ratings?
Also, what has been your experience buying used, and what is the lowest acceptable rating to get substantially noise free (tic/pops) records? Please let me know, thanks.
jmr
Here is a start.

Remember however, that any grading scale, whether it be the Goldmine or AudiogoN, is open to different interpretations by different individuals.

John
for the most part, records are graded visually by collectors. a visual nm which is under m- or m is as low as you really need to go. its a crapshoot.
The generally recognized grading scale was established by Goldmine and a complete version of it can be found at the link below. According to that scale a grade of VG+ for the vinyl, as opposed to the cover, would meet your listening criteria. However, my experience in buying many records in auctions is that most records which are graded VG+ by sellers in fact are overgraded and do have playback issues. There even are many sellers out there, including some with great feedback records, who grade records as mint- or near mint which still have audible problems. The bottom line is that you have to know your seller in order to know what you are getting. The only caveat to that is that the risk is a bit lower for 80's/90's pressings of common records.

http://www.recordcollectorsguild.org/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=17&page=1