It has to be factually correct, so if you were sacked for stealing, they can say this. They can't give an opinion so can't say 'I think he was stealing but never caught him'.
Have you been a bad employee? If so, most would give no reference. Why dont you discuss the possible reference. The new employer may only wish to know i.e that you had good attendance/good timekeeping/honesty/worked hard/. If you were none of those thigs - dont call me. But it would be unkind for an old employer not helping you get another start.