In my opinion, they are the races to avoid.
Stick to where a trainer has only one runner in the race, that's a pretty good guide in most events other than major Group races.
Wrote a piece a few years back about certain trainers who have a habit of leaving sole acceptors when they look likely to win or go close.
I wrote the following in Jan 2006, it was republished by a glossy mag in Feb 2006 without permission, so here it is
"I've done some analysis of John Hawkes, and thought I'd share some useless,
some salient, and some startling information I've gathered.
I've analysed 933 John Hawkes winners.
These were all not first up from a spell and were not first starters.
13.72% of winners carried same weight from last start.
40.19% of winners dropped in weight from last start.
46.09% of winners rose in weight from last start.
24.44% of winners ran over the same distance as last start 58.52% of winners
went up in distance from last start 17.04% of winners dropped in distance
from last start
100% of winners started within 30 days
87.78% of winners started within 21 days 47.27% of winners started within 14
days 6.64% of winners started within 7 days
27.33% of winners ran at the same track last start 72.67% of winners ran at
a different track last start
52.84% of winners ran in Sydney
21.76% of winners ran in Brisbane
21.22% of winners ran in Melbourne
4.18% of winners ran in Adelaide
85.53% of winners ran at a Metro track last start 14.47% of winners ran at a
Country track last start
28.51% of winners had one run since spell *** (second up) 24.54% of winners
had two runs since spell 19.29% of winners had three runs since spell 12.43%
of winners had four runs since spell 15.22% of winners had five or more runs
since spell
2.57% of winners were on Fast going
70.95% of winners were on Good going
17.15% of winners were on Dead going
5.68% of winners were on Slow going
3.54% of winners were on Heavy going
65% of winners were ridden by 5 regularly engaged jockeys 45% of winners
were ridden by not regularly engaged jockeys There was a large volume of
jockeys who only ever won once for John Hawkes - and never won again
And now for the most astounding stat of all, which made it all
worthwhile.....
I analysed the success of sole John Hawkes runners in a race compared with
multiple runners and here's what happened.....
78.56% of winners were sole Hawkes runners 19.51% of winners were dual
Hawkes runners 1.71% of winners were a trio of Hawkes runners 0.21% of
winners were a quad of Hawkes runners 0% of winners were a quin of Hawkes
runners 0% of winners where there were 7 Hawkes runners
So only 21.44% of winners came from multiple runners."
This data is obviously outdated, but it gives a pretty good insight into spotting signals.