Initially, I’ll suggest it’s both bad practice and under many cases, not permitted under many ‘domestic’ radio service licenses.
Now exactly where you legally stand depends on how you extend usage beyond service intended use and for what reason.
Assuming your license neither permits or prohibits non domestic usage of a domestic usage defined radio service, you’ll be a fair victim of objection and fabricated claims of misuse - so even where not prohibited, outright obvious extended use such as business use isn’t recommended.
Where limited permitted extended business use is permitted, if you use with respect that the domestics usage should be respected as primary use, you should be able to draw a balance.
Where limited permitted or not defined specifically, there are some generic guidelines which can help keep you out of the firing line of irrational objecters.
Under no circumstances be witnessed/heard selling or promoting products you supply or represent at a potential sales/supply level. This will pretty much define you as abusing fair usage at best, and mostly destroy any limited permitted extended use privilege.
It’s usually fine and no problem to use as a communications infrastructure, just respect that you don’t have any squatter occupancy right over any frequency/channel/tone or selcall or code selective usage even if you regularly or persistently use one.
Combining those two, a fair usage in a sales /supply usage would be where agents/reps use it for infrastructure traffic, where they can radio details back to base for quote/estimate verification or to obtain non-standard quoted and estimates, provided the exchange of information and provision of the supply info is between staff (infrastructure use) and the customer doesn’t obtain their request via the radio service.
In fact, many casual and non sales/supply infrastructure type exchanges are usually permissable at some level where it can be seen as conversation or general radio intermittent traffic exchanges.
Sometimes, outside of sales/supply exchange usage, you may find that fair infrastructure usage could be subject to other limits such as maximum permitted group usage sizes and maximum number of associated adjacent cross-group interchange/messaging (third party messaging and exchanges) etc.
Subsequently, most domestic radio services deny repeater usage, so group ops using repeaters as range extenders is often a dead option. What isn’t often respected is rights of cross-linking or cross-band usage to link diverse groups of multiple diverse domestic and commercial services - as a rule of thumb for safety, irrespective of license and service, if it’s neither adddressed in general or formally addressed in prohibition terms, avoid such things as you cannot reliably ensure the other parties are legit users of their linked radio service at the very least lowest rung of the unnecessary complications ladder.
Of course, this is all subject to specific permissions and variations of services and licenses, within regional/economic political territories.