Looking at the race you rated:

2 INVICTUS PHOENIX $3.6 = 29%
5 HUN CAN YOU $4.3 = 23%
7 COCO LIGHTNING $4.8 = 21%
4 SHE'S BOSSY $14 = 7%
6 WHY NOT BOB $16 = 6%
3 DR. ROCHELLE $16 = 6%
1 DR. EVEREST $16 = 6%
8 SALEGREYS STUNNA $40 = 2%

I rounded above.

Above is a 100% market. Assuming your ratings are good (and I expect they are) I will assume you have a 10% deviation on strike rate.

So the new prices should be:

2 INVICTUS PHOENIX $5.30 = 19%
5 HUN CAN YOU $7.70 = 13%
7 COCO LIGHTNING $9.10 = 11%
4 SHE'S BOSSY $100 = 1% = NO HOPE
6 WHY NOT BOB $100 = 1% = NO HOPE
3 DR. ROCHELLE $100 = 1% = NO HOPE
1 DR. EVEREST $100 = 1% = NO HOPE
8 SALEGREYS STUNNA $100 = 1% = NO HOPE

Of these anything that is 1% is a no bet.

That leaves 2, 5 and 7 as bets. All of those were under the value odds on unitab so this race would be a no bet race using unitab odds. I checked Betfair advantage tool and found Number 2 was $8.34 and Number 5 was $9.38. So 2 bets at value on this race and a nice profit.

Now turn this on its head for laying.

2 INVICTUS PHOENIX $2.55 = 39%
5 HUN CAN YOU $3.00 = 33%
7 COCO LIGHTNING $3.20 = 31%
4 SHE'S BOSSY $5.88 = 17%
6 WHY NOT BOB $6.25 = 16%
3 DR. ROCHELLE $6.25 = 16%
1 DR. EVEREST $6.25 = 16%
8 SALEGREYS STUNNA $8.33 = 12%

Those are your acceptable laying prices. I don't follow the dogs anymore so I checked betfair advantage tool for the odds. It showed Number 7 was an acceptable lay at $2.88.

Hope this gives you some insight to value betting and how that race was profitable.