Let us know exactly what you're doing so we can figure it out; Esa (at Estibot) uses a secure source for the name searches on his site, so if you're ONLY using Estibot and your searches are being seen we'll let him know pronto, as his security has been breached somehow.
But if you're doing something else as well, like doing your searches at a registrar before or after the Estibot search, that's the more likely culprit... let us know
Edit: I reread your first post and now I think I get it... you're searching names on Estibot, saving them in the bulk save area, then pasting them all into Dynadot's bulk search tool... and then they are being tasted/sniffed by olsz very quickly, right? How quick is quick... do you mean within a couple hours or a few minutes? If it's within a couple hours, I've lost a lot of names that way from sniffers, when I've searched at namecheap, godaddy, moniker, etc. But if it's within a few minutes, that's getting scary.
Incidentally, have you contacted this person olsz? Domain sniffers often (but not always) have a link to contact them in case they've taken a name you really want and have a use for. Domain sniffing is starting to get frowned upon, they see possible legislation/lawsuits on the horizon, and often make it possible to turn over the name to you if you inquire. You can always try that but no guarantees of course.
