I´d agree absentee bids are not always terribly wise. I´ve always avoided left bids whenever possible, myself, but sometimes needs must. Not all auction houses misuse them but their imperative is to maximise the take and some aren´t as ethical as others in that regard. It´s obviously very easy to take the highest left bid (or near to it) as if it´s an offer to buy at that price regardless, rather than only being the highest price someone will go to in competition with everyone else. But although I do think left bids are taken improper advantage of sometimes, you can´t be sure it´s happened just because there aren´t a procession of bids leading to that. It´s perfectly feasible and reasonable for a starting bid to be quoted as a single figure if/when that´s the next bid up from the second highest left bid and/or relative to the reserve. I am not sure you entirely understand how that works, Maxfrost.
I´m absolutely sure there´s shill bidding on the likes of Ebay. It´s quite understandable, though, in some circumstances. Ebay doesn´t allow for fair and reasonable protection of things being sold, so that can be the only recourse. Trying to sell something good via auction on Ebay can be like throwing whatever to the tender mercies of the equivalent of a bunch of kindergarten kids who would think a Rembrandt should still be able to be bought for pennies. It´s frightening, really! I dislike the practice of keeping bidding details private, but Ebay enforces that. And much worse than just hiding shill bidding is the denial of any facility to contact a fraudulently deceived buyer to tell them they´ve been fraudulently deceived. So instead, too often there´s just yet more great feedback left by yet another unknowing idiot who doesn´t understand what it is they´ve bought in real life, let alone from photos.
I sell some things on Ebay, but very rarely by auction. I have tried occasionally out of curiosity. I did recently with a good watercolour that I´d presumed would be being actively searched for by the many interested parties there should have been. A similar, but not as nice other, sold at an appropriate standard auction for the equivalent of about £3000. In the right gallery it would be hugely more than that. I didn´t put shill bids in there, so it only got 2 watchers and one bid of 99p (!) and there was no way I could leave it to finish and sell with that level of interest. So I had no option but to stop the listing. Both watchers contacted me about it, and one of them was a sweet guy who knew what it was and would have loved to buy it but wasn´t in the market for something so expensive and hadn´t been going to bid more than £100. The other very unpleasant guy started at £30, as if I should have been grateful to get that, but went up to £1000 even after I made it very clear I wasn´t selling it to him at any price, and was really shirty about the listing having been stopped at all because he seemed to think he had some sort of right to have it thrown away at him for peanuts. And that´s what Ebay is full of, silly people who´ll see/pay £1500 for the likes of a worthless fake Picasso, and who then also think that something good that´s actually real should also be supposed to be able to be bought for the same sort of minuscule fraction of genuine value.