If they are clear in advance about what comes out, then it's OK, imo.
Also, there are reasons other than obfuscation for doing this apparent adding with the right hand and taking back with the left hand.
We have an 8-ball tournament coming up March 7-9 that is $60 entry, $2500 added. We take $10 out of each entry as a green fee. You might say that if we have 100 players (and thus take $1000 back in green fees) then we're really only adding $1500. And you might ask why don't we drop the green fee and just add $1500?
The reason goes to the real purpose of the added money. We are saying to the player who might take time off of work, who might travel and have a hotel that WE and not the player will assume the risk of a low turnout. In other words, even if only 8 people show up for the tournament (because of weather or conflicting events or whatever), that player making the commitment to come knows thew prize fund will be over $2500.
If a tournament turnout is high, the added money becomes a less and less important part of the prize fund--relatively speaking.
That is one fine word. I had to google it for it's actually meaning, but I feel much smarter. Hopefully, I can pronounce correctly.