Same here,corruption and missing textures with 13.2 beta.

Also i have drop down fps which make the game lag,those issues wasn't there few updates ago.

Screenshots:
http://steamcommunity.com/profiles/76561198052496864/screenshots/

Processeur :
Fabricant : GenuineIntel
Vitesse : 3701 MHz
8 processeurs logiques
4 processeurs physiques
HyperThreading : Pris en charge
FCMOV : Pris en charge
SSE2 : Pris en charge
SSE3 : Pris en charge
SSSE3 : Pris en charge
SSE4a : Non pris en charge
SSE41 : Pris en charge
SSE42 : Pris en charge

Réseau :
Vitesse du réseau :

Version du système d'exploitation :
Ubuntu 12.10 (64 bits)
Nom du noyau : Linux
Version du noyau : 3.5.0-23-generic
Éditeur du serveur X : The X.Org Foundation
Version du serveur X : 11300000
X Window Manager: Xfwm4
Steam Runtime Version:

Carte vidéo :
Pilote : ATI Technologies Inc. AMD Radeon HD 6900 Series

Version du pilote : 4.2.12171 Compatibility Profile Context 12.10.17
Profondeur de couleur du bureau : 24 bits par pixel
Taux de rafraîchissement du moniteur : 60 Hz
ID fabricant : 0x1002
ID périphérique : 0x6719
Nombre de moniteurs : 1
Nombre de cartes vidéo logiques : 1
Résolution de l'affichage principal : 1920 x 1080
Résolution du bureau : 1920 x 1080
Taille de l'affichage principal : 27,48" x 15,43" (31,50" diag)
                                        69,8cm x 39,2cm (80,0cm diag)
Mémoire vidéo principale non détecté

Carte son :
Périphérique audio : Realtek ALC889

Mémoire :
RAM : 3937 Mo

Divers :
Langue de l'interface : Français
LANG: fr_FR.UTF-8
Micro : Not set
Espace disque total disponible : 93908 Mo
Plus grand bloc disponible sur le disque dur : 12150 Mo

Logiciel installé :

Rapports d'échec récent :

I had your problems (artifacts, missing textures) with 13.2 beta too. With 13.1 it doesn't look that bad, at least I don't remember having artifacts with 13.1. With 13.2 I had the problems on every second map.

Something similar here. Not everytime, it happens randomly on random maps.
I never saw it in normal gamemodes, only in MVM, but I play MVM much more.
My solution is disconnect from a server and reconnect (or just start any new game).

Catalyst 13.1

Processor Information:
Vendor: AuthenticAMD
Speed: 1400 Mhz
4 logical processors
4 physical processors
HyperThreading: Unsupported
FCMOV: Supported
SSE2: Supported
SSE3: Supported
SSSE3: Supported
SSE4a: Supported
SSE41: Unsupported
SSE42: Unsupported

Network Information:
Network Speed:

Operating System Version:
Linux Mint 13 Maya (64 bit)
Kernel Name: Linux
Kernel Version: 3.6.5-030605-generic
X Server Vendor: The X.Org Foundation
X Server Release: 11103000
X Window Manager: Mutter
Steam Runtime Version:

Video Card:
Driver: ATI Technologies Inc. AMD Radeon HD 6520G

Driver Version:  4.2.12002 Compatibility Profile Context 9.012
Desktop Color Depth: 24 bits per pixel
Monitor Refresh Rate: 59 Hz
VendorID:  0x1002
DeviceID:  0x6760
Number of Monitors:  1
Number of Logical Video Cards:  2
Primary Display Resolution:  1366 x 768
Desktop Resolution: 1366 x 768
Primary Display Size: 13.54" x 7.60"  (15.51" diag)
                                        34.4cm x 19.3cm  (39.4cm diag)
Primary VRAM Not Detected

Sound card:
Audio device: ATI R6xx HDMI

Memory:
RAM: 3418 Mb

Miscellaneous:
UI Language: English
LANG: en_US.UTF-8
Microphone: Not set
Total Hard Disk Space Available: 581188 Mb
Largest Free Hard Disk Block: 151673 Mb

Installed software:

Recent Failure Reports:
Sun Feb 17 18:00:47 2013 GMT: file ''/tmp/dumps/assert_20130217190043_1.dmp'', upload yes: ''CrashID=bp-e1eb2f8b-1342-4737-8e75-c95322130217''

Same issue here on both 13.1 and 13.2 Beta. Artifacts and missing textures in random maps -

Processor Information:
Vendor: GenuineIntel
Speed: 3201 Mhz
12 logical processors
6 physical processors
HyperThreading: Supported
FCMOV: Supported
SSE2: Supported
SSE3: Supported
SSSE3: Supported
SSE4a: Unsupported
SSE41: Supported
SSE42: Supported

Network Information:
Network Speed:

Operating System Version:
Ubuntu 12.10 (64 bit)
Kernel Name: Linux
Kernel Version: 3.5.0-23-generic
X Server Vendor: The X.Org Foundation
X Server Release: 11300000
X Window Manager: Compiz
Steam Runtime Version:

Video Card:
Driver: ATI Technologies Inc. AMD Radeon HD 7900 Series

Driver Version:  4.2.12171 Compatibility Profile Context 12.10.17
Desktop Color Depth: 24 bits per pixel
Monitor Refresh Rate: 59 Hz
VendorID:  0x1002
DeviceID:  0x6798
Number of Monitors:  3
Number of Logical Video Cards:  2
Primary Display Resolution:  2560 x 1600
Desktop Resolution: 4960 x 1600
Primary Display Size: 25.24" x 15.79"  (29.76" diag)
                                        64.1cm x 40.1cm  (75.6cm diag)
Primary VRAM Not Detected

Sound card:
Audio device: Realtek ALC898

Memory:
RAM: 32151 Mb

Miscellaneous:
UI Language: English
LANG: en_US.UTF-8
Microphone: Not set
Total Hard Disk Space Available: 87524 Mb
Largest Free Hard Disk Block: 57367 Mb

Installed software:

Recent Failure Reports:

Some more screenshots...

http://steamcommunity.com/sharedfiles/filedetails/?id=128314874
http://steamcommunity.com/sharedfiles/filedetails/?id=128314832

The artifacts and missing textures definitely appear on specific maps, so it's not random. The new Catalyst 13.2 Beta 6 doesn't help.

Also having the same issue as described in the above screenshots.

On a HD6950 with Catalyst 13.3 beta 2,no more missing/corrupted texture and no more fps drop too.