Well in the absence of a 'massive' reply, I'll digress a little and theorise that CP was addressing this question, "Has lay betting corrupted horse racing?"

Remember that arranging a horse to lose, is a lot easier than arranging one to win! With the advent of lay betting, profit can be made for such a result. It's a question often considered when a short priced odds on shot falls over?

Is there any evidence to be gleaned from recent history of implied strike rate vs actual, and comparing same with stats from pre Betfair?

I've just read a paper:

Have Betting Exchanges Corrupted Horse Racing?
Alasdair Brown∗ Fuyu Yang† University of East Anglia University of East Anglia
October 3, 2014

Makes for interesting reading, but for those who like to read the end of a book first, .........there was NO evidence to support such a notion.