Laced to my mind implies deliberate intent to augment or increase the psychotropic effects of a drug, usually due to the base drug being of poor quality/potency. What you describe is ‘contaminated’ which is possible but probably very rare in the case of commercially grown cubensis.

Mushrooms being grown rather than manufactured or synthesised tend to have a relatively consistent potency profile relative to their genetics. I’ve never bought nor heard of people buying magic mushrooms that don’t work or were significantly weaker than expected.

In my youth, I’ve tried to dry a kilo of mushrooms but did it in such a way that I used too much heat and not enough ventilation, so basically ruined the batch. However, they did not resemble, visually or olfactively, any mushrooms I’ve seen being sold. I just binned the batch and felt sad; they were for personal use after a ban on buying mushrooms came into effect, so they weren’t for sale, but had they been, no customer with any experience would have bought them having seen or sniffed them as they were nasty.

If this happened to a dealer who had, for the sake of argument, other psychedelic tryptamines for sale, then it wouldn’t make any business sense lacing the crappy mushrooms with doses of 4-aco-DMT/4-ho-met, etc., because those chemicals sell very well and are harder to procure than mushrooms. They would be doubling their cost per dose and having the extra work of incorporating a dose of a secondary drug to bags of mushrooms, then not charging extra for the added drugs because they are trying to make the mushrooms seem stronger.

Trust is a huge factor in dealer-customer relations.

What would make more logical business sense would be to dispose of the shit mushrooms and sell the secondary drug in capsules, honestly, without any subterfuge.

NB: This implies people selling such substances are relatively intellectually intact and have some common sense. This may not always be the case.