where do you draw the line on what is tresspassing?

[Western]

I think if it's behind a fence, generally the seller prefers you to contact him if your interested, look but don't touch idea. Possibly they feel somewhat more security with the product behind the fence or it's the only way to display it.

I have gone up to the house where something was posted for sell, if no one is home and I am "really" interested I will leave a note with my #.

I've known my neighbor for 6 years and we are good friends, but I don't cross his fence unless it was an emergency ( fire or what not) with out his permission.

Guess I'm just to "hardline"..LOL

 

[Car Doc]

I look at it like this- if they are that lazy or afraid as to not put where I can plainly see it and walk around it they wont get my look at it they don't want to sell it very bad.

OR its in a bad area and they are afraid someone will steal something off it either way its not for me if I have to cross fences etc had too many encounters with farm dogs etc not worth it to me.

I have been known a time or several to find a neighbor and ask about something I see in a farm yard etc but I wont jump any ones fence or trespass and that's how I expect to be treated.

 

[TracTrac]

To answer the OPs question. That depends on the area.
I have relatives in Oklahoma that never lock their doors. Here in Alabama a burglar will knock on someones door, ask for directions to a persons house that does not exist or if there is no answer they will break in. It's not against the law to knock on someones door. That's where a gate comes in handy. I don't own any fences or gates. Never know when you might need 911 services.
To properly sell an item in a yard (again depending on the area) place a sign large enough for the buyer to read your phone number.