Have a look at the following pics and decide which of them is a former grow-operation.
That was four different homes. Need more clues?
Ok, here are more pics from the same houses (in the same sequence of house, as the first lot).
If you picked house 1 - you were right!
If you picked house 2 - you were right!
If you picked house 3 - you were also right!
And if you picked house 4, yep, you were right. They were all former grow-ops!
Just by looking at the pictures, it's unlikely that you can tell.
And without the help of an experienced Realtor or professional home inspector, you the buyer might be unaware of what it is you're getting yourself into.
Now, the home may well indeed be completely re-mediated and back to a normal house, but wouldn't you want someone on your team who knows where and what to check to help address your concerns?
The above pics were from "declared" former grow-ops, where the listing Realtor declared it in the Broker's comments. By law, the listing Realtor is obligated to disclose this kind of information if it's shared with him/her. But what if the seller chose not to disclose this information to their own Realtor? That's why you really need a Realtor working on your behalf.
If you're the buyer and decide that you're going to deal directly with the seller's agent instead of getting your own agent to represent and protect your interests, thinking you're going to save a few bucks in a reduced commission, that decision could end up costing you far, far more in the long run.
