can you tell anothers proxy bid?

Only by bidding up to it!

you can check and see what else that buyer has bid on and won. Then from that you can sometimes make a judgement call to guesstimate what they might have bid on the item you're bidding on. Not very scientific but you can tell how they bid, and if they bid high or not.

Sara's got the idea. Look at the other bidder's auction record, being sure to include closed auctions, regardless of who won them. You can usually tell whether a bidder "nibbles" one bid increment at a time, for instance, or adds one increment plus an odd amount like 77 cents, or ups the ante by considerably more. You can also notice when the bidder places these bids, that is, at what point in the auction, and whether he/she is a sniper also. When outbid, does the bidder (a) give up entirely; (b) jump right back in with a counter-bid; (c) wait for a while to see who else bids, if anyone, before weighing in with a counter-bid...well, you get the idea.

As Sara says, it's not possible to narrow it down to an exact number, but armed with the sort of information above you have the opportunity to frame a snipe that will react to the other bidder's tendencies. It's sure a lot better than going in "blind."

Hi hmmm, very interesting but how do you look at a bidders auction record ?

Easy. From any eBay page look for "Search" at the top. Click on that. On the resulting page look for a tab "By Bidder" and click on that. On the page you get by doing that put the username or the e-mail address of the person you want to check up on in the box provided and be sure to check the box that you want to see closed auctions, regardless of who won. With a little practice you'll actually get more information from the auctions the guy lost than the ones he won. Anyway, when you've set up your search click on the "Search" button at the end of the userid space. You'll get every auction the person has bid in for the past 30 days. Check out a few or all of them, wins and losses alike, going to the bid history on each to see your target's bidding patterns. You'll find that nearly every proxy bidder has a pattern that he has developed unconsciously. (Snipers know better. )

Questions? Come back here and ask 'em, any time. There are a lot of very experienced, skilled snipers in the Forum.