Lots of custodial moms change when the ncp gets married, Personally I feel they are threatened (insecure in themselves)
My dh's ex used to not send clothes either, we purchased clothes for our house and at the end of the viist them returned to moms in the clothing they came in.
Document all the time you have had our child, this will help with the status quo to keep your child like you have been (up until the time you got married and how it has changed)
Most courts WILL give you holidays (they usually alternate odd-even years etc)
It is hard to prove her living conditions, if you get a gaurdiam ad litem involved mom will surely get her house clean, at least for the visit.
**These are my opinions, they are not legal advice**