I’ve 
seen service companies sorely tempted (and I confess I’ve been there) to take on whatever work is being offered. This is how web developers become print brokers and graphic designers fancy themselves brand managers. It’s a farce. In the midst of a meeting, somebody asks whether the project can be extended to include an additional service, and the business quietly asks themselves “Why not?” reasoning that it can’t be all that hard. “Of course,” they tell the client. “We do that too!”
The thing is, by diluting the thing that the business was supposed to be sharp at, they attempt to become a jack-of-all-trades, thinking this will open them up to all sorts of new business. But in the end, isn’t it more likely that the business ends up presenting themselves as an “odd-jobs” handyman who will take on just about any little thing for $15 an hour? For some businesses that’s okay. If that’s what you’re after.
In the bad old days (and to this day in bad companies) there was a real fear of leaving “money on the table” in any given transaction. Companies would attempt to gouge every last dollar out of a client, believing that “money now” was far better than “money later”. In time, the customer would leave the supplier when they got a far better price.
Hoovering up all the “loose work” from a customer, regardless of one’s area of expertise is somewhat similar. In time, the customer realizes that they can get it done better elsewhere.
Right you are, Brad. Better to tell the customer the truth, I figure. “No, that’s not our specialty, but I can certainly recommend someone.” You score points with the customer and the expert to whom you refer. Nice whuffie.