How do I correctly append/prepend a description for an AD user?

Question

I'm still a little new to PowerShell, but experienced enough to be able to search the net and formulate my own script, but I've been stuck on this one part for an entire day now.  Here's what I'm trying to accomplish using PowerShell 4:
I've already run the following script to produce a list of users in our domain that have not logged into the network for more than 90 days (This is done as a separate requirement of the business):
search-adaccount -accountinactive -usersonly -timespan "105" | Export-Csv "k:\Inactive90 $(get-date -f yyyy-MM-dd).csv"
So I have a csv file with the following headers (and data below it, but removed for business privacy):
AccountExpirationDate Enabled LastLogonDate LockedOut Name ObjectClass ObjectGUID PasswordExpired PasswordNeverExpires UserPrincipalName
I need to pre-pend the date of disable within the description of the AD user.  The problem that I'm experiencing is that the resultant description that I'm receiving is that the first part of the description is what I expect, where it says
Last login more than 90 days, Disabled on WHATEVERDATE, but the second part of the description, where I'd expect to see the original description of the AD user, I see this:
@{Description=PREVIOUS DESCRIPTION TEXT HERE}, so from what I can gather, the original description is getting read as an array, and is thus being output as an array.  So I tried forcing it into a string by putting [string] at the front of the
$Desc variable.  No dice.
So the resultant description that I'm currently left with is:
Last login more than 90 days, Disabled on WHATEVERDATE, @{Description=PREVIOUS DESCRIPTION TEXT HERE}
I obviously don't want the brackets and @ sign and Description= there.  I'd like it to read as:
Last login more than 90 days, Disabled on WHATEVERDATE, PREVIOUS DESCRIPTION TEXT HERE
Below is the code for a script that I've written.  Any help is much appreciated.
$cred = Get-Credential
$Date = Get-Date -UFormat %D
$InactiveUsers = Import-csv ".\test.csv"
foreach ($User in $InactiveUsers)
Disable-ADAccount -Identity $User.ObjectGUID -Credential $cred
$Desc = Get-ADUser -Identity $User.ObjectGUID -Properties Description -Credential $cred | Select-Object -Property Description
Set-ADUser -Identity $User.ObjectGUID -Credential $cred -Description "Last login more than 90 days, Disabled on $Date, $Desc"

Answer 1

This should work:
$cred = Get-Credential
$Date = Get-Date -UFormat %D
$InactiveUsers = Import-csv ".\test.csv"
foreach ($User in $InactiveUsers)
Disable-ADAccount -Identity $User.ObjectGUID -Credential $cred
$Desc = Get-ADUser -Identity $User.ObjectGUID -Properties Description -Credential $cred | Select-Object -ExpandProperty Description
Set-ADUser -Identity $User.ObjectGUID -Credential $cred -Description "Last login more than 90 days, Disabled on $Date, $Desc"
Instead of
Select -Property Description
use
Select -ExpandProperty Description
that will give you the actual data of the property instead of what is called a NoteProperty that gives you the brackets.
I hope this post has helped!