Do disputes impact your credit profile and scores? You betcha! I have seen where many "credit repair companies" will just go in an dispute everything listed on your credit report. I suppose that is one way to go about it. I don't love that plan.
A dispute will temporarily improve your credit score because that "thing" you are disputing is removed from the credit scoring algorithm (that negative mark is temporarily removed) for the first 30 days. If it is found that your dispute is not valid, the remarks stay attached to that tradeline.
When it comes to a mortgage, when disputes are listed, and over a specific amount, it can cost you where your dispute has to be removed or you must pay down that amount of the collection a dispute might be attached to.
You really don't want to be making changes to your credit profile in the middle of a loan application as it can impact your approval.
Here are the numbers for each of the credit reporting bureaus to call and request the removal of the dispute language:
Equifax 800-493-1058
Experian 800-846-5279
Transunion 800-916-8800
questions@creditkristi.com