Don't and this is a big don't, appear too interested in any animal before it's auctioned. The seller will probably be near and will ask a friend to bid you up. Certainly don't mention aloud a price you're prepared to go up to!! How do I know this?
I'm sorry to hear you've been tweaked like this, Sylvia - but in 'regular' (weekly / general conventional livestock) auctions, this is something that is very much frowned upon. If the auctioneer realises this is happening (and they probably will - they know all the sellers and all the regular buyers, and what they buy
), then s/he will ignore the 'runner' (one who is running up the bidding) and a very stern quiet word will be had with both parties later on.
I would certainly agree that it is unwise to discuss your likely top bid, though.
In terms of letting the buyer know of your interest or not - again, I think there is more to be gained by talking to the buyer beforehand (how are they bred, what is the farm like, are they used to ticks, what vaccination regime are they on, etc) than to be lost. I cannot speak for all types of seller, and of course there are bad eggs in every walk of life, but on the whole I find farming folk to be genuine people.