@Jiri B. Its a little different situation but when buying occupied rentals we almost always make the offer with a healthy chuck of earnest money and make them contingent on viewing/inspecting the property. It helps get a foot in the door before others and also lets them know you're serious before they bother with a showing. It really just depends on what you're buying it for. Unless you are waiving any contingencies you or someone you trust will be seeing it at some point so really no harm, no foul.
Some agents don't like it but the good ones around here understand that even writing 5 offers that turn into a $15k+ paycheck is still a good use of their time, especially if its a semi-recurring thing. Now, if you don't close on them every so often then yes, you will loose realtors pretty fast.
As far as lowball offers go, it just depends on the market. In hot markets most people will just ignore your offer. You might get lucky or you might go through 15 agents that drop you because you haven't closed on anything.