You can tell from the titles of the dogs in the pedigree whether the dog is field-bred, show-bred, or BYB. Pedigree: Dusty Snickerdoodle Madison MX MXJ AAD EAC OGC OJC RS-E GS-O JS-O CL4-R CGC
Dusty - he's BYB. One great-grandsire and one great-great-grandsire have conformation titles, but other than that there are no titles. All those dorky names on the dam's side are also typical BYB (sunshine, delight, golden girl, etc). Pedigree: Tanbark's Number Two Pencil OA, OAJ, NF, JS-O, RS-O, GS-N, WCDex, SRD
Stephanie's Quiz, field bred. HRCH, MH, JH, WCX, FTCH, AFTCH, FDHF, and *** are hunting/field titles (OTCH, UDX and OBHF are obedience titles). Pedigree: BIS/BISS Am/Can CH Rush Hill Xcentuate th' Pawsitiv SDHF
There's a dog someone posted about a while back who's show-bred. The BIS, BISS, and CH titles are for conformation shows.
As for knowing about particular dogs, it just comes from looking at the pedigrees of dogs that are doing well in agility and seeing which lines are most frequently behind good agility dogs. Obviously there are some exceptions (no one in their right mind would go buy a puppy because its pedigree included Sunshine Golden Girl Princess and all those lovely dogs in Dusty's pedigree) but when particular lines are showing up again and again in the pedigrees of good agility dogs it usually means they'd be a good pick for agility. Pedigree: MACH2 Shoreland's Wild Streak CD, MX, MXJ, CanCD Pedigree: MACH7 ADCh Tanbark's One More Time MX MXJ NF MAD SAM SM RM GM CGC EJC EGC EAC Pedigree: MACH4, ADCH FlashPaws Runaround Sue XF, SACH, JCH, GCH - Bronze, RCH, ADHF
There are some good agility Goldens that I can think of right now. You can see that OTCH Meadowpond Stardust Reggie is in all of them, I don't have time to look for more dogs that are in them all but there are probably more. Also if you click on "View genetic information for ..." you can see that AFC Holway Barty OS is the most influential in the first two, and OTCH Meadowpond Stardust Reggiw is the most influential in the third (I'm not entirely sure about the whole coefficient of inbreeding thing, but I think it means that he is in the pedigree the most times). Look at the pedigrees of dogs that do especially well in agility and agility dogs that you like, and you start to get an idea of the pedigree you're looking for.